The number of MPD installs on Android < 5.0 is negligible, and that
API version introduces lots of useful features for MPD.

Fixes the NFS client build, closes #305.

Only _WIN32 is defined by the compiler, and WIN32 is not standardized
and may be missing.

Closes #169

Apparently, connecting a socket to a loopback address can block on
Windows, and a non-blocking socket will return WSAEINPROGRESS.  This
broken PoorSocketPair() in commit 2119e4fd, which made the socket
non-blocking right from the start.  This fix postpones the
ioctlsocket(FIONBIO) call until after the connect().

Closes #134

It does not do much harm - but it causes an unnecessary (failing)
system call.