Only turn on AP_DEBUG if we're using gcc.

The AP_DEBUG flavor of the cmd_func declarations is not portable.
Last night Roy removed the check for gcc before turning on AP_DEBUG.
Interestingly (or not :) ) the AP_DEBUG flavor of cmd_func compiles
cleanly on gcc but the non-AP_DEBUG flavor doesn't. The non-AP_DEBUG
flavor compiles cleanly with Tru64 cc and AIX xlc but the AP_DEBUG
flavor doesn't. (On Tru64 we get a bunch of warnings with the
AP_DEBUG flavor but at least it compiles; the same cannot be said of
AIX xlc.)

Perhaps we should use a symbol other than AP_DEBUG to distinguish
between the cmd_func flavors.  Then AP_DEBUG can be turned on
regardless of compiler.  The new flag can be turned on for gcc+
--enable-maintainer-mode, or perhaps for gcc always since the non-
AP_DEBUG flavor won't compile cleanly with gcc.  (what a mess; this
probably wouldn't work right for different levels of gcc anyway)


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@89096 13f79535-47bb-0310-9956-ffa450edef68