r300: abort shader compilation early on loops and branches

r300: abort shader compilation early on loops and branches

R300/R400 GPUs can't do it in hardware and all the lowering should have
happened in NIR already, there is no point in wasting CPU time, just to
abort later when emitting.

Reduces CPU time for dEQP run by ~25% for RV370. The wallclock time is
now just slighly above 1 minute at 10 threads, mostly determined by the
long-running dEQP-GLES2.functional.flush_finish.* tests.

Signed-off-by: Pavel Ondračka <pavel.ondracka@gmail.com>
Reviewed-by: Filip Gawin <filip@gawin.net>
Tested-by: Filip Gawin <filip@gawin.net>
Reviewed-by: Emma Anholt <emma@anholt.net>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/19766>