Update DemangleConfig.h to better mangle LLVM's version.

There's no need for the demangling bits to depend on libc++ internals,
in the same way they don't when compiled as part of LLVM.

llvm-svn: 359534
GitOrigin-RevId: 2520530bb05c8b78fd9064a117e63fb0a61a785a
1 file changed