Create new src/ap sibdirectory for the ap_*() routines, and

	tweak things to use it.  So far only ap_signal() has been
	moved here, but that's enough to get htdigest to build.
	Other functions can move here over time.

PR:		512, 905, 1252, 1308
Reviewed by:	Dean Gaudet, Roy Fielding


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/branches/1.3.x@79611 13f79535-47bb-0310-9956-ffa450edef68