Add msvc.c and msvc.h to build git under MSVC.
Signed-off-by: NFrank Li <lznuaa@gmail.com>
Signed-off-by: NMarius Storm-Olsen <mstormo@gmail.com>
Acked-by: NJohannes Sixt <j6t@kdbg.org>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>