glamor: fix XVideo run with GLES

For now, it sets .version=120, which prevents shader from compiling on ES.
We just force version of shaders to be always 100 on ES, because we use
only 120 shaders on ES anyway, and all shaders works.

Signed-off-by: Konstantin Pugin <ria.freelander@gmail.com>

Reviewed-by: Adam Jackson <ajax@redhat.com>