refs.c: handle REFNAME_REFSPEC_PATTERN at end of page

When a ref crosses a memory page boundary, we restart the parsing
at the beginning with the bytewise code.  Pass the original flags
to that code, rather than the current flags.

Reported-By: Øyvind A. Holm <sunny@sunbase.org>
Signed-off-by: David Turner <dturner@twitter.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
refs: Fix valgrind suppression file

Add all of the ways in which check_refname_format violates valgrind's
expectations to the valgrind suppression file; remove an assumption about
the call chain of check_refname_format from same.

Signed-off-by: David Turner <dturner@twitter.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>