glsl/parser: Handle "#version 300 es" directive.

glsl/parser: Handle "#version 300 es" directive.

Note that GLSL 1.00 is selected using "#version 100", so "#version 100
es" is prohibited.

v2: Check for GLES3 before allowing '#version 300 es'

v3: Make sure a correct language_version is set in
_mesa_glsl_parse_state::process_version_directive.

Signed-off-by: Paul Berry <stereotype441@gmail.com>
Signed-off-by: Ian Romanick <ian.d.romanick@intel.com>
Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>
Acked-by: Carl Worth <cworth@cworth.org>