On the svn-auth-x509 branch, fix typo.

* subversion/libsvn_subr/x509parse.c:
  (x509_skip_ext): compare the pointers not the pointer and value.


git-svn-id: https://svn.apache.org/repos/asf/subversion/branches/svn-auth-x509@1605785 13f79535-47bb-0310-9956-ffa450edef68