Maemo/Meego buildfix. Compiles but requires arm ffmpeg.
Support block transfer bpp mismatch on gles2.

When we don't have GLES2.
Merge pull request #6234 from unknownbrackets/gpu-blocktransfer

Support block transfer bpp mismatch on gles2
Stop clearing the buffer after blitting to it.

This only appeared to work because destroying an fbo unbinds the active
one.
Ignore vfb->format for older display buffers.

Fixes video in Tales of Phantasia X.