Partially revert r1203859: use a fixed string

Partially revert r1203859: use a fixed string
per module as the proxy_function instead of
the macro __FUNCTION__ which is not C89.

There's no real loss of information, because all
of the calls are in the same scgi handler function.

All proxy modules apart form SCGI already use the
upper case scheme in the analogous calls.

git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@1210124 13f79535-47bb-0310-9956-ffa450edef68