Followup to r21369 and r21621, fixing path-test test 13 on Cygwin.
Followup to r21369 and r21621, fixing path-test test 13 on Cygwin.

* subversion/tests/libsvn_subr/path-test.c
  (test_canonicalize): Don't run the tests for paths with drive letters on
    Cygwin, since Windows is the only target that is expected to treat them
    in the special way that these tests are expecting.

jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion