Log Message:
Re-instate the cmake configure check for whether -latomic is
required to gain access to 8-byte atomics.  Add a hacks.mk file
to pull in devel/libatomic on powerpc ports.  The reason is that
even though llvm itself doesn't need or use 8-byte atomics, other
programs refer to this installed CheckAtomic cmake file and may
indeed both need and use 8-byte atomics.
Verified that llvm still builds on NetBSD/macppc 9.0.
Bump PKGREVISION to 1.