modules: new internal MAGNUM_DATA_INSTALL_DIR.

Will be used by examples etc. to install various auxiliary data.

modules/FindMagnum.cmake

@@ -113,6 +113,7 @@
 #  MAGNUM_*_LIBRARY_RELEASE     - Release version of given library, if found
 #  MAGNUM_BINARY_INSTALL_DIR    - Binary installation directory
 #  MAGNUM_LIBRARY_INSTALL_DIR   - Library installation directory
+#  MAGNUM_DATA_INSTALL_DIR      - Data installation directory
 #  MAGNUM_PLUGINS_[DEBUG|RELEASE]_INSTALL_DIR - Plugin installation directory
 #  MAGNUM_PLUGINS_FONT_[DEBUG|RELEASE]_INSTALL_DIR - Font plugin installation
 #   directory
@@ -566,6 +567,7 @@ find_package_handle_standard_args(Magnum
 include(${CORRADE_LIB_SUFFIX_MODULE})
 set(MAGNUM_BINARY_INSTALL_DIR ${CMAKE_INSTALL_PREFIX}/bin)
 set(MAGNUM_LIBRARY_INSTALL_DIR ${CMAKE_INSTALL_PREFIX}/lib${LIB_SUFFIX})
+set(MAGNUM_DATA_INSTALL_DIR ${CMAKE_INSTALL_PREFIX}/share/magnum)
 set(MAGNUM_PLUGINS_DEBUG_INSTALL_DIR ${MAGNUM_LIBRARY_INSTALL_DIR}/magnum-d)
 set(MAGNUM_PLUGINS_RELEASE_INSTALL_DIR ${MAGNUM_LIBRARY_INSTALL_DIR}/magnum)
 set(MAGNUM_PLUGINS_FONT_DEBUG_INSTALL_DIR ${MAGNUM_PLUGINS_DEBUG_INSTALL_DIR}/fonts)