Change mutex defines so it should work on OS that don't have the _NP mutex...

Change mutex defines so it should work on OS that don't have the _NP mutex types.  Also move the #defines up so we don't need to duplicate them


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@2678 65c4cc65-6c06-0410-ace0-fbb531ad65f3