nir: add missing group_memory_barrier handling
Totals from 2 (0.00% of 127638) affected shaders:
VGPRs: 164 -> 168 (+2.44%)
CodeSize: 18420 -> 18756 (+1.82%)
Instrs: 3658 -> 3700 (+1.15%)
Cycles: 82912 -> 83080 (+0.20%)
VMEM: 70 -> 69 (-1.43%)
PreVGPRs: 155 -> 168 (+8.39%)
Signed-off-by: Rhys Perry <pendingchaos02@gmail.com>
Reviewed-by: Caio Marcelo de Oliveira Filho <caio.oliveira@intel.com>
CC: <mesa-stable@lists.freedesktop.org>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/4889>