Fix some the svn_uri_canonicalize and svn_canonicalize_path tests on Windows. Remove the UNC-path test cases for the svn_path functions, as those are not canonical uris.
Patch by: rhuijben me (Testcases by me.)
* subversion/libsvn_subr/dirent_uri.c (canonicalize): Only consider '//' as the start of a UNC path when working with dirents, not uris.
* subversion/tests/libsvn_subr/dirent_uri-test.c (test_path_dirname, test_path_canonicalize, test_path_is_ancestor, test_path_is_canonical): Comment out UNC-path test cases. The svn_path functions aren't documented to support UNC paths, and they don't work for all svn_path functions either.