doc: add another dumpster truck of workarounds to the Android guide.

doc/platforms-android.dox

@@ -55,16 +55,18 @@ for a cleaner setup.
     -   [android-ndk](https://aur.archlinux.org/packages/android-ndk/)
     -   [android-sdk-build-tools](https://aur.archlinux.org/packages/android-sdk-build-tools/)
     -   [android-sdk-platform-tools](https://aur.archlinux.org/packages/android-sdk-platform-tools/)
-    -   [android-platform-24](https://aur.archlinux.org/packages/android-platform-24/)
+    -   [android-platform-29](https://aur.archlinux.org/packages/android-platform-29/)
     -   [android-sdk-cmake](https://aur.archlinux.org/packages/android-sdk-cmake/)
 
 Gradle requires Android SDK version of CMake, which is currently at version
 3.10. See below for an experimental way to @ref platforms-android-system-cmake "use the system CMake"
 instead. On the other hand, while it's possible to use the CMake from Android
-SDK to build Magnum itself, the following guide is written with CMake 3.16 and
+SDK to build Magnum itself, the following guide is written with CMake 3.20 and
-newer in mind, which has Android NDK r19+ support built-in. In older versions
+newer in mind, which has Android NDK r22+ support built-in. CMake 3.16 to 3.19
-you'd need to supply a toolchain file instead and the configuration values are
+supports only NDK until r21, in even older versions you'd need to supply a
-different.
+toolchain file instead and the configuration values are different, see the
+@ref platforms-android-cmake-too-old "related troubleshooting section" for more
+information.
 
 @section platforms-android-console Building and running console applications
 
@@ -73,31 +75,15 @@ you have Magnum installed in the NDK path as described in @ref building-cross-an
 build your project as below. Adapt paths to your system, Android ABI and
 version and NDK location as needed.
 
-<b></b>
-
-@m_class{m-note m-warning}
-
-@par
-    Unfortunately, CMake before version 3.20 needs extra help with
-    `CMAKE_FIND_ROOT_PATH` and `CMAKE_FIND_LIBRARY_CUSTOM_LIB_SUFFIX` to
-    correctly find Android libraries, as shown below. Otherwise it falls back
-    to looking in native system locations. Again, adapt them to your system,
-    Android ABI and version and NDK location as needed.
-@par
-    CMake 3.20 and newer [is now able to detect everything on its own](https://gitlab.kitware.com/cmake/cmake/-/merge_requests/5357)
-    and you don't need to supply these anymore.
-
 @m_class{m-console-wrap}
 
 @code{.sh}
 mkdir build-android-arm64 && cd build-android-arm64
 cmake .. \
     -DCMAKE_SYSTEM_NAME=Android \
-    -DCMAKE_SYSTEM_VERSION=24 \
+    -DCMAKE_SYSTEM_VERSION=29 \
     -DCMAKE_ANDROID_ARCH_ABI=arm64-v8a \
     -DCMAKE_ANDROID_STL_TYPE=c++_static \
-    -DCMAKE_FIND_ROOT_PATH=/opt/android-ndk/toolchains/llvm/prebuilt/linux-x86_64/sysroot \
-    -DCMAKE_FIND_LIBRARY_CUSTOM_LIB_SUFFIX=/aarch64-linux-android/24 \
     -DCMAKE_BUILD_TYPE=Release
 cmake --build .
 @endcode
@@ -421,11 +407,8 @@ x86_64      | &lt;nk&gt;/platforms/android-&lt;version&gt;/arch-x86_64/usr
 After that, you can add the additional ABIs to the `abiFilters` list in your
 `build.gradle`.
 
-For example, building Magnum for 32-bit and 64-bit ARM with SDK version 24
+For example, building Magnum for 32-bit and 64-bit ARM with SDK version 29
-could look like this. The same note regarding CMake 3.20 applies here --- on
+could look like this, assuming CMake 3.20+ being used.
-versions before, you need the `CMAKE_FIND_ROOT_PATH` and
-`CMAKE_FIND_LIBRARY_CUSTOM_LIB_SUFFIX` variables as well (and have them in sync
-with the ABI and API version level), on 3.20 and newer you can omit them.
 
 @m_class{m-console-wrap}
 
@@ -433,13 +416,11 @@ with the ABI and API version level), on 3.20 and newer you can omit them.
 mkdir build-android-arm && cd build-android-arm
 cmake .. \
     -DCMAKE_SYSTEM_NAME=Android \
-    -DCMAKE_SYSTEM_VERSION=24 \
+    -DCMAKE_SYSTEM_VERSION=29 \
     -DCMAKE_ANDROID_ARCH_ABI=armeabi-v7a \
     -DCMAKE_ANDROID_STL_TYPE=c++_static \
     -DCMAKE_BUILD_TYPE=Release \
-    -DCMAKE_INSTALL_PREFIX=<ndk>/toolchains/llvm/prebuilt/linux-x86_64/sysroot/usr \
+    -DCMAKE_INSTALL_PREFIX=<ndk>/toolchains/llvm/prebuilt/linux-x86_64/sysroot/usr
-    -DCMAKE_FIND_ROOT_PATH=<ndk>/toolchains/llvm/prebuilt/linux-x86_64/sysroot \
-    -DCMAKE_FIND_LIBRARY_CUSTOM_LIB_SUFFIX=/arm-linux-androideabi/24
 cmake --build . --target install
 
 cd ..
@@ -447,13 +428,11 @@ cd ..
 mkdir build-android-arm64 && cd build-android-arm64
 cmake .. \
     -DCMAKE_SYSTEM_NAME=Android \
-    -DCMAKE_SYSTEM_VERSION=24 \
+    -DCMAKE_SYSTEM_VERSION=29 \
     -DCMAKE_ANDROID_ARCH_ABI=arm64-v8a \
     -DCMAKE_ANDROID_STL_TYPE=c++_static \
     -DCMAKE_BUILD_TYPE=Release \
-    -DCMAKE_INSTALL_PREFIX=<ndk>/toolchains/llvm/prebuilt/linux-x86_64/sysroot/usr \
+    -DCMAKE_INSTALL_PREFIX=<ndk>/toolchains/llvm/prebuilt/linux-x86_64/sysroot/usr
-    -DCMAKE_FIND_ROOT_PATH=<ndk>/toolchains/llvm/prebuilt/linux-x86_64/sysroot \
-    -DCMAKE_FIND_LIBRARY_CUSTOM_LIB_SUFFIX=/aarch64-linux-android/24
 cmake --build . --target install
 @endcode
 
@@ -769,9 +748,47 @@ gradle build
 @subsection platforms-android-cmake-too-old CMake or NDK is too old
 
 While the minimal CMake version that's required for building Magnum for Android
-is 3.7, NDK r19 and newer need at least CMake 3.16 to work. For older NDKs you
+is 3.7, NDK r22 and newer need at least CMake 3.20, and attempting to use CMake
-might want to grab at least CMake 3.9.2, as it [fixes an issue with the Clang toolchain](https://gitlab.kitware.com/cmake/cmake/issues/17253).
+3.19 or older with NDK r22+ will greet you with an error similar to the
+following, as NDK r22 removed certain deprecated internal paths:
+
+@m_class{m-console-wrap}
+
+@code{.shell-session}
+CMake Error at /usr/share/cmake-3.17/Modules/Platform/Android-Determine.cmake:176 (message):
+  Android: The API specified by CMAKE_SYSTEM_VERSION='29' does not exist in
+  the NDK.  The directory:
+
+    /opt/android/sdk/ndk/22.1.7171670/platforms/android-29
+
+  does not exist.
+Call Stack (most recent call first):
+  /usr/share/cmake-3.17/Modules/CMakeDetermineSystem.cmake:129 (include)
+  CMakeLists.txt:70 (project)
+@endcode
+
+NDK r19 to r21 need at least CMake 3.16 to work, and CMake before version 3.20
+needs extra help with `CMAKE_FIND_ROOT_PATH` and
+`CMAKE_FIND_LIBRARY_CUSTOM_LIB_SUFFIX` to correctly find Android libraries,
+otherwise it falls back to looking in native system locations. An example is
+shown below, adapt them to your system, Android ABI and version NDK location
+as needed.
+
+@m_class{m-console-wrap}
+
+@code{.sh}
+cmake .. \
+    -DCMAKE_SYSTEM_NAME=Android \
+    -DCMAKE_SYSTEM_VERSION=29 \
+    -DCMAKE_ANDROID_ARCH_ABI=arm64-v8a \
+    -DCMAKE_ANDROID_STL_TYPE=c++_static \
+    -DCMAKE_FIND_ROOT_PATH=/opt/android-ndk/toolchains/llvm/prebuilt/linux-x86_64/sysroot \
+    -DCMAKE_FIND_LIBRARY_CUSTOM_LIB_SUFFIX=/aarch64-linux-android/29 \
+    -DCMAKE_BUILD_TYPE=Release
+@endcode
 
+For NDKs before r19 you might want to grab at least CMake 3.9.2, as it
+[fixes an issue with the Clang toolchain](https://gitlab.kitware.com/cmake/cmake/issues/17253).
 With NDK r18 and older you'll need to additionally supply
 `-DCMAKE_ANDROID_NDK_TOOLCHAIN_VERSION=clang`, on the other hand the
 `-DCMAKE_FIND_ROOT_PATH` isn't needed --- CMake is able to figure out the paths