coregl_fastpath: Keep frame buffer binding state synchronization

coregl_fastpath: Keep frame buffer binding state synchronization

Calling function fastpath_glBindFramebuffer() with target
GL_FRAMEBUFFER indicates bind to GL_READ_FRAMEBUFFER and
GL_DRAW_FRAMEBUFFER in the meantime.

If GL driver supports GL_READ_FRAMEBUFFER_BINDING and
GL_DRAW_FRAMEBUFFER_BINDING, clue state
gl_framebuffer_binding_read and gl_framebuffer_binding_draw
are both necessary to keep state synchronization, or state
gl_framebuffer_binding is enough.

Add judgement on current_ctx->gl_framebuffer_binding_draw_used
to make sure read and draw are both supproted.

Signed-off-by: Zhaowei Yuan <zhaowei.yuan@samsung.com>
Change-Id: Ia74ff7b4d67dfaf0b2cf00e97d996e4bb2dd640d