Android: Use JNI for getting post-processsing shaders

The Java implementation of getting the list of post-processing
shaders only looked in the Sys folder and not the User folder.
This could be fixed in the Java implementation, but it's
simpler to just call the C++ implementation instead.

Source/Android/jni/CMakeLists.txt

@@ -1,10 +1,11 @@
 add_library(main SHARED
+  Config/NativeConfig.cpp
+  Config/PostProcessing.cpp
   GameList/GameFile.cpp
   GameList/GameFile.h
   GameList/GameFileCache.cpp
   IniFile.cpp
   MainAndroid.cpp
-  NativeConfig.cpp
   WiiUtils.cpp
 )