checkpatch: add warning for non-lore mailing list URLs

The lkml.org, marc.info, spinics.net, etc archives are not quite as useful
as lore.kernel.org because they use different styles, add advertising, and
may disappear in the future.  The lore archives are more consistent and
more likely to stick around, so prefer https://lore.kernel.org URLs when
they exist.

[bhelgaas@google.com: only warn if we see "http" before the archive hostname]
  Link: https://lkml.kernel.org/r/20221114224315.GA939630@bhelgaas
Link: https://lkml.kernel.org/r/20221019202843.40810-1-helgaas@kernel.org


Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Peter Collingbourne <pcc@google.com>
Cc: Andy Whitcroft <apw@canonical.com>
Cc: Dwaipayan Ray <dwaipayanray1@gmail.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Lukas Bulwahn <lukas.bulwahn@gmail.com>
Cc: Randy Dunlap <rdunlap@infradead.org> # build-tested
Cc: Joe Perches <joe@perches.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>