builtin-remote.c and parse-options.c both have a skip_prefix() function,
for the same purpose. Move parse-options's one to git-compat-util.h and
let builtin-remote use it as well.
Signed-off-by: NMiklos Vajna <vmiklos@frugalware.org>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>