Android fixes

Maintaining GEMRB_Android.mk manually isn't great, I'll rewrite it in the next few weeks.

The "SDL.h" vs. "SDL/SDL.h" issue stems from how I set up the build environment; I'm not really sure how to solve this, but #ifdef'ing everywhere isn't a great solution either.

The GemRB.java deletions come from the realisation that copying any old file named "GemRB.cfg" from the sdcard root doesn't really help with trying to get a running configuration. Instead there should/will be a "Import existing config" in the configuration GUI, which I should be able to get started on in the next few weeks as well.