Revert to previous handling of getaddrinfo()

Use the system gettaddrinfo function when possible as before.  Tested on
GNU, Cygwin, MinGW on Linux, and MinGW on Windows.  Under MinGW the
replacement getaddrinfo is used.  Perhaps this is an area for
investigation to be certain MinGW really doesn't supply getaddrinfo.
This reverts some of the patches from Remi Chateauneu in commit
60019c9.  This fixes build issues encountered building the Windows
binary daily snapshots.

Enabled static library build by default at configure time.

Fixed pthread library linking for the ars backend on MinGW.