Implement LWG 2936: Path comparison is defined in terms of the generic format

This patch implements path::compare according to the current spec. The
only observable change is the ordering of "/foo" and "foo", which orders
the two paths based on having or not having a root directory (instead
of lexically comparing "/" to "foo").

llvm-svn: 349881
GitOrigin-RevId: 1425485773534fa2431c22e660a6922142db9a66
3 files changed