Unfortunately, OpenSolaris died when Oracle took over Sun Microsystems. However, out of the ashes rose the Illumos project, which took over powering platforms like Nexenta and spawned new distributions such as OpenIndiana. The Illumos-powered platforms gained Pkgsrc through the Illumos Pkgsrc Project, which boasted an impressive 6600 built packages soon after getting launched.
GNAT-AUX was already available on Pkgsrc, but it only works on platforms in which a bootstrap compiler is provided. Before this week, this covered exactly four platforms:
I had previously built a flawless GNAT-AUX on an obsolete OpenSolaris version SXCE 130. It was fairly trivial to built a static bootstrap compiler on the latest version of OpenIndiana (oi_151a).
The lang/gnat-aux package has been updated to support the x86 Solaris target, and also updates all supported platforms to provide working runtime symbolic traceback. It just missed the 2011Q3 branch, so it's only available in the pkgsrc trunk.