mesa/st: reduce size of state->st bitmask
mesa/st: reduce size of state->st bitmask

In d035d50 this changed to 64b.. which I'm pretty sure was
unintentional.  Revert it back to 32b so the entire state struct
is a nice round 64b.

(Note sure that it would actually be measurable, but I did notice
that check_state() was hot in some benchmarks.)

Signed-off-by: Rob Clark <915c10c999604870200b6defbe633d857c856ca0@gmail.com>
Reviewed-by: Marek Olšák <8c7344a1abdb103e79ecfd488098373070c3c70e@amd.com>

metora/MesaGLSLCompiler,metora/MesaGLSLCompiler,metora/MesaGLSLCompiler