Fix SHARED_CORE feature for HPUX platform: We now use extension `.sl'

instead of `.so' and `SHLIB_PATH' instead of `LD_LIBRARY_PATH' on this
platform to make the braindead HPUX linker happy. Notice, for the module
DSOs we don't have to use this, because these are loaded manually (and
not via HPUX' dld).

PR: 2905, 2968


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/branches/1.3.x@82068 13f79535-47bb-0310-9956-ffa450edef68