Implement Jeff's idea for an autoconf-defined symbol to enable the special

command function prototype stuff. AP_DEBUG is always set in maintainer mode
and AP_DEBUG_HAVE_GCC is set when the compiler is GCC.

Submitted by: Jeff Trawick


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@89102 13f79535-47bb-0310-9956-ffa450edef68