MSVC: Fix build by adding missing termios.h dummy

A use of this header file was introduced in eb80042c (Add missing #include
to support TIOCGWINSZ on Solaris, 2010-01-11).
Signed-off-by: NJohannes Sixt <j6t@kdbg.org>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

compat/vcbuild/include/termios.h

+/* Intentionally empty file to support building git with MSVC */