Android: Add clang --target= flag to compiler predefines command

When we set `CMAKE_<LANG>_COMPILER_TARGET` to the Android target
architecture, add it to `CMAKE_<LANG>_COMPILER_PREDEFINES_COMMAND` also.
This is needed to make moc predefines aware of `__ANDROID__`.

Fixes: #18425

Modules/Platform/Android-Clang.cmake

@@ -40,5 +40,6 @@ macro(__android_compiler_clang lang)
   endif()
   if(NOT CMAKE_${lang}_COMPILER_TARGET)
     set(CMAKE_${lang}_COMPILER_TARGET "${_ANDROID_ABI_CLANG_TARGET}")
+    list(APPEND CMAKE_${lang}_COMPILER_PREDEFINES_COMMAND "--target=${CMAKE_${lang}_COMPILER_TARGET}")
   endif()
 endmacro()