GLES2: Fix (re-implement) multi-texture in OpenGLES2 codepath.

With this implementation, mipmapping must be disabled in the OpenGLES2
codepath to avoid black textures.

Texture mirror flag is enabled in the in OpenGLES2 codepath to fix
messed up textures like the horse's cheeks in both Zelda games.

extracted from
https://github.com/mupen64plus-ae/mupen64plus-ae/commit/33d250b926141dfd1de72d19b61c8e1b3d7ffda8
GLES2: Use config file to disable mipmapping rather than hard code.
GLES2: Fix (re-implement) fog/alpha shaders in OpenGLES2 codepath.

extracted from
https://github.com/mupen64plus-ae/mupen64plus-ae/commit/33d250b926141dfd1de72d19b61c8e1b3d7ffda8
Remove unneeded macro in osal_opengl.
Add hack-fix to show last heart and map arrows in Zelda OoT & MM.

This affects both OpenGL and OpenGLES2 codepaths.
Merge pull request #1 from littleguy77/gles2-shader-texture-fixes

Gles2 shader texture fixes
Merge pull request #2 from littleguy77/zelda-missing-heart-fix

Add hack-fix to show last heart and map arrows in Zelda OoT & MM.
Minor formatting nits in OpenGL ES2 shader program.
Remove duplicate function call.
Merge pull request #3 from littleguy77/cleanup

Minor nits
rice: Remove hard-coding on anisotropic-filter flag.

Anisotropic filtering only applies if mipmapping is enabled. But we
already disable mipmapping via the config file, since it's currently
broken.  If we fix mipmapping then we can return to the topic of aniso
filtering.

See also
99147f0afdf3ae82928163f0fdbfe158beee9f29
build: Add android makefile.
android: Add android edition customizations.
video-rice: Sync with upstream.