Platform: users of the AndroidApplication don't need the glue.

Made the include private and added some public headers instead.

modules/FindMagnum.cmake

@@ -510,8 +510,6 @@ foreach(_component ${Magnum_FIND_COMPONENTS})
             # Android application dependencies
             if(_component STREQUAL AndroidApplication)
                 find_package(EGL)
-                set_property(TARGET Magnum::${_component} APPEND PROPERTY
-                    INTERFACE_INCLUDE_DIRECTORIES ${ANDROID_NATIVE_APP_GLUE_INCLUDE_DIR})
                 set_property(TARGET Magnum::${_component} APPEND PROPERTY
                     INTERFACE_LINK_LIBRARIES android EGL::EGL)
 

src/Magnum/Platform/AndroidApplication.cpp

@@ -27,6 +27,7 @@
 
 #include <Corrade/Utility/AndroidStreamBuffer.h>
 #include <Corrade/Utility/Debug.h>
+#include <android_native_app_glue.h>
 
 #include "Magnum/Version.h"
 #include "Magnum/Platform/Context.h"

src/Magnum/Platform/AndroidApplication.h

@@ -31,7 +31,6 @@
 
 #include <memory>
 #include <EGL/egl.h>
-#include <android_native_app_glue.h>
 
 #include "Magnum/Magnum.h"
 #include "Magnum/Tags.h"
@@ -42,9 +41,13 @@
 #error this file is available only on Android build
 #endif
 
+#include <android/input.h>
+
 /* Undef Xlib nonsense which might get pulled in by EGL */
 #undef None
 
+struct android_app;
+
 namespace Magnum { namespace Platform {
 
 /** @nosubgrouping