In GLES2, we cannot do GL_RED or GL_RG without GL_EXT_texture_rg.
So, add check for GL_EXT_texture_rg to make it working. Also add
a yuv2 pixman format into render.h to make Xv yuv rendering works.
Signed-off-by: Yuriy Vasilev <uuvasiliev@yandex.ru>
Reviewed-by: Adam Jackson <ajax@redhat.com>
Reviewed-by: Emma Anholt <emma@anholt.net>