(1) Rename getClangSubversionRevision() to getClangRevision(), and

    have it return a StringRef instead of an integer (to be more VCS
    agnostic).

(2) Add getClangFullRepositoryVersion(), which contains an
    amalgamation of the repository name and the revision.

(3) Change PCH to only emit the string returned by
    getClangFullRepositoryVersion() instead of also emitting the value
    of getClangSubversionRevision() (which has been removed).  This is
    functionally equivalent.

More cleanup to version string generation pending...

llvm-svn: 94231