Fix clang compiler detection on OS X
Fix clang compiler detection on OS X

check-tools.pl was hard-wired to expect the Apple compiler version string which
doesn't make much sense, especially for a LLVM project.

The correctness and value of these compiler version checks still isn't clear
following this build fix but they are retained for now.

git-svn-id: f99161ee8ccfe2101cbe1bdda2220bce2ed25485@202029 91177308-0d34-0410-b5e6-96231b3b80d8

llvm-mirror/openmp,llvm-mirror/openmp,llvm-mirror/openmp,llvm-mirror/openmp,llvm-mirror/openmp