radeonsi/gfx9: always wrap GS and TCS in an if-block (v2)

radeonsi/gfx9: always wrap GS and TCS in an if-block (v2)

With merged ESGS shaders, the GS part of a wave may be empty, and the
hardware gets confused if any GS messages are sent from that wave. Since
S_SENDMSG is executed even when EXEC = 0, we have to wrap even
non-monolithic GS shaders in an if-block, so that the entire shader and
hence the S_SENDMSG instructions are skipped in empty waves.

This change is not required for TCS/HS, but applying it there as well
simplifies the logic a bit.

Fixes GL45-CTS.geometry_shader.rendering.rendering.*

v2: ensure that the TCS epilog doesn't run for non-existing patches

Cc: mesa-stable@lists.freedesktop.org
Reviewed-by: Marek Olšák <marek.olsak@amd.com>