glsl: Bail on parsing if the #version directive is bogus.

glsl: Bail on parsing if the #version directive is bogus.

If we didn't successfully parse the #version line, there's no point in
continuing with parsing and compiling: it's already failed.

Furthermore, it can actually be harmful: right after handling #version,
we call _mesa_glsl_initialize_types(), which checks state->es_shader and
language_version.  If it isn't valid, it hits an assertion failure.

Fixes Piglit's "invalid-version-es."  When processing "#version 110 es",
our code set state->es_shader and state->language_version = 110.  It
then properly determined that this was invalid and flagged an error.
Since we continued anyway, we hit the assertion mentioned above.

NOTE: This is a candidate for the 9.1 branch.

Reviewed-by: Matt Turner <mattst88@gmail.com>
Signed-off-by: Kenneth Graunke <kenneth@whitecape.org>