anv/cmd_buffer: Rework descriptor dirtying in set_subpass
anv/cmd_buffer: Rework descriptor dirtying in set_subpass

We have a DIRTY_RENDER_TARGETS flag and that makes a lot more sense than
just dirtying fragment descriptors.  We're checking for it in some of the
gen7 code but unfortunately, nothing was setting it and it didn't do what
it was supposed to do in cmd_buffer_flush_state.

Signed-off-by: Jason Ekstrand <68c46a606457643eab92053c1c05574abb26f861@jlekstrand.net>

metora/MesaGLSLCompiler,metora/MesaGLSLCompiler,metora/MesaGLSLCompiler