config.mak.dev: workaround gcc 12 bug affecting "pedantic" CI job

config.mak.dev: workaround gcc 12 bug affecting "pedantic" CI job

Originally noticed by Peff[1], but yet to be corrected[2] and planned to
be released with Fedora 36 (scheduled for Apr 19).

  dir.c: In function ‘git_url_basename’:
  dir.c:3085:13: error: ‘memchr’ specified bound [9223372036854775808, 0] exceeds maximum object size 9223372036854775807 [-Werror=stringop-overread]
   3085 |         if (memchr(start, '/', end - start) == NULL
        |             ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Fedora is used as part of the CI, and therefore that release will trigger
failures, unless the version of the image used is locked to an older
release, as an alternative.

Restricting the flag to the affected source file, as well as implementing
an independent facility to track these workarounds was specifically punted
to minimize the risk of introducing problems so close to a release.

This change should be reverted once the underlying gcc bug is solved and
which should be visible by NOT triggering a warning, otherwise.

[1] https://lore.kernel.org/git/YZQhLh2BU5Hquhpo@coredump.intra.peff.net/
[2] https://bugzilla.redhat.com/show_bug.cgi?id=2075786

Signed-off-by: Carlo Marcelo Arenas Belón <carenas@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>