nir: extract out helper macros for running passes

Note these are a bit uglier, due to avoidance of GNU C extensions.  But
drivers which do not need to be built with compilers that don't support
the extension can wrap these macros with their own.

Signed-off-by: Rob Clark <robclark@freedesktop.org>
Reviewed-by: Jason Ekstrand <jason@jlekstrand.net>
2 files changed