separate logic specific to building Apache DSOs from logic needed

when anybody's DSOs should be built (e.g., via apxs) so that on a
few platforms with special issues third-party modules can be loaded
as long as mod_so is built into httpd


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@92343 13f79535-47bb-0310-9956-ffa450edef68