When processing a 'SetEnv' directive, warn if the environment variable name...

When processing a 'SetEnv' directive, warn if the environment variable name includes a '='. It is likely a configuration error.   PR 60249

git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@1795635 13f79535-47bb-0310-9956-ffa450edef68