* We can have expressions that become true if a regex pattern in the expression

  does NOT match. In this case val is NULL and we should just set the value for
  the environment variable like in the pattern case.


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@1786235 13f79535-47bb-0310-9956-ffa450edef68