fix crash in util_fcgi.c

 *) mod_proxy_fcgi, mod_fcgid: Fix crashes in ap_fcgi_encoded_env_len() when
    modules add empty environment variables to the request. PR60275.
    [<alex2grad AT gmail.com>]

Submitted By: <alex2grad AT gmail.com>]
Committed By: covener




git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@1775487 13f79535-47bb-0310-9956-ffa450edef68