In the C tests, add a utility error-checking macro.
In the C tests, add a utility error-checking macro.

* subversion/test/svn_test.h
  (SVN_TEST_ASSERT_ERROR): New macro.

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