I've had a report of a sparc64 system where cc1 generates illegal
instructions. We still have to diagnose this properly, but instead of
hosing all sparc64 boxes out there, fall back to libgcc to prevent more
damage.
Reported by: Florian Smeets
Not doing so may cause all sorts of random libraries to expose
libcompiler_rt's functions, which should of course not be done.
Discussed with: kan, kib
