One issue I repeatedly have with 3rd party module builds is that

  One issue I repeatedly have with 3rd party module builds is that
  they may choose to build a platform-default library with the usual
  platform-default extension, as part of the compilation process.

  Modules built on HP/UX with the .sl extension, on OSX with .dylib,
  or on OS2 or Win32 with .dll are perfectly legitimate loadable
  modules, but don't pass muster with apxs.

  This patch allows any of the common source library extensions to
  be passed in, but makes .so the explicit target.  The behavior
  already works for .la origin files with an .so target name.

git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@170383 13f79535-47bb-0310-9956-ffa450edef68