Delete custom_upload/data arguments to do_create_bitmap.

These were unused since al_create_custom_bitmap was removed.
Change display create_bitmap method to accept new bitmap parameters as args.
Add _al_create_bitmap_params that takes new bitmap format/flags as arguments.
ogl: Use proxy bitmap when locking writable backbuffer regions on GLES.

This is a cleaner version of the idea in
ogl_unlock_region_backbuffer_via_texture.  When trying to lock a region
of the backbuffer for writing, we create a proxy video bitmap and lock
that instead.  Upon unlocking, the proxy bitmap is updated, then drawn
onto the backbuffer.  For now we don't keep the proxy bitmap across a
single lock/unlock pair.

There was another code path using glDrawTex which was used on iOS.
It has been removed.

Trent did some testing of ex_lockbitmap on iOS.  As of this commit
it is partially broken on iOS, but better than 5.1.7.
ogl: Log when dirty bitmaps are backed up.
cmake: Set GLES variables for IPHONE.
speed: Disable strict prototype warnings on Android as well.
android: Fix typo in check for ALLEGRO_CFG_OPENGL_PROGRAMMABLE_PIPELINE.
Drop example GLSL shaders to #version 100.

GLES supports #version 100 but not #version 120.
ex_shader: Call init_platform_specific.
ex_shader_multitex: Call init_platform_specific.
ex_prim_shader: Support touch input.