Any local references get cleaned up when returning to the JVM,
but some of the functions in AndroidCommon return to C++ rather
than the JVM, and functions with loops risk running into the
limit of how many simultaneous local references are allowed.
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.
The functions with "UTF" in the name use "modified UTF-8" rather
than the standard UTF-8 which Dolphin uses, at least according
to Oracle's documentation, so it is incorrect for us to use them.
This change fixes the problem by converting between UTF-8 and
UTF-16 manually instead of letting JNI do it for us.
Deduplicates code, and gets rid of some problems the old code had
(such as: bad performance when calling native functions, only one
disc showing up for multi-disc games, Wii banners being low-res,
unnecessarily much effort being needed for adding more metadata).
JosJuice