strbuf: clarify dependency
refs.h was once needed but is no longer so as of 6bab74e7fb8 ("strbuf:
move strbuf_branchname to sha1_name.c", 2010-11-06). strbuf.h was
included thru refs.h, so removing refs.h requires strbuf.h to be added
back.
Signed-off-by: Calvin Wan <calvinwan@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
authored by