Allow ipv6 addresses encoded in urls in the common
http://[::1]/svn/repos format.
by extending our canonical urls a tiny bit.

* subversion/libsvn_subr/dirent_uri.c
  (canonicalize,
   svn_uri_is_canonical): Allow lower case [] ipv6 addresses.

* subversion/tests/libsvn_subr/dirent_uri-test.c
  (uri_canonical_tests): Add a few ipv6 testcases.


git-svn-id: https://svn.apache.org/repos/asf/subversion/trunk@1454047 13f79535-47bb-0310-9956-ffa450edef68