Allow different file name extensions for the shared core and shared modules.

Set HPUX to use .sl for the core & .so for modules.
Set OS/2 to use .dll for both.
Reviewed by:	Ryan Bloom


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/branches/1.3.x@84459 13f79535-47bb-0310-9956-ffa450edef68