winsock2.h must always be included before windows.h

winsock2.h must always be included before windows.h

Some GNULIB headers (eg unistd.h) will often need to include
winsock2.h for various symbols. There is a rule that winsock2.h
must be included before windows.h. This means that any file
which does

  #ifdef WIN32
  #include <windows.h>
  #endif
  #include <unistd.h>

is potentially broken. A simple rule is that /all/ includes of
windows.h must be matched with a preceding include of winsock2.h
regardless of whether unistd.h is used currently

Signed-off-by: Daniel P. Berrange <berrange@redhat.com>