Refactor winsock initialization into a separate function

Refactor winsock initialization into a separate function

The winsock library must be initialized. Since gethostbyname() is the
first function that calls into winsock, it was overridden to do the
initialization. This refactoring helps the next patch, where other
functions can be called earlier.

Signed-off-by: Martin Storsjo <martin@martin.st>
Acked-by: Johannes Sixt <j6t@kdbg.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>