Various patches, to enable Asterisk to once again compile on Mac OS X.

One note on defining _POSIX_C_SOURCE:  while this feature test macro
works to require certain behaviors on Linux, it works differently on *BSD
platforms to REMOVE certain API calls that are not in the POSIX specification,
such as vasprintf(3).  Thus, defining it while depending upon vasprintf (and
other extensions to the POSIX standard) to be defined is a recipe to ensure
that Asterisk is only buildable on Linux.

Hence, this define which was meant to INCREASE portability, effectively
ensures the opposite.


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@214863 65c4cc65-6c06-0410-ace0-fbb531ad65f3