Provide POSIX semantics for socket timeout options on W32.
* lib/setsockopt.c: Convert struct timeval to milliseconds on W32.
* lib/getsockopt.c: Convert milliseconds to struct timeval on W32.
* modules/setsockopt: Depend on sys_time module for struct timeval.
* modules/getsockopt: Depend on sys_time module for struct timeval.
Signed-off-by: Simon Josefsson <simon@josefsson.org>