This will allow callers to specify more options (e.g.,
leaving echo on). The original git_getpass becomes a slim
wrapper around the new function.
Signed-off-by: NJeff King <peff@peff.net>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

This is currently in connect.c, but really has nothing to
do with the git protocol itself. Let's make a new source
file all about prompting the user, which will make it
cleaner to refactor.
Signed-off-by: NJeff King <peff@peff.net>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>