aarch64: Fix aarch64-tune.md (re)generation [PR105144]

aarch64: Fix aarch64-tune.md (re)generation [PR105144]

As I wrote in the PR, our Fedora trunk gcc builds likely after r12-7842
change are now failing (lto1 crashes).
What happens is that when one bootstraps into an empty build directory
(or set of them), mddeps.mk doesn't exist yet and so Makefile doesn't
include it.  When building from an empty dir, that is usually not a big
issue, it is enough when various build directory files depend on just
$(srcdir)/config/aarch64/aarch64.md, those files don't exist and
aarch64.md does, so they are built, so is mddeps.mk.
But because the other dependencies aren't there (in particular
$(srcdir)/config/aarch64/aarch64-tune.md ), the
s-aarch64-tune-md rule isn't invoked to regenerate that file and the
r12-7842 commit reordered aarch64-cores.def entries but didn't commit
regenerated aarch64-tune.md.  Because it is just reordering in
aarch64-tune.md, it actually doesn't matter and bootstraps succeeds.
But then during make install, mddeps.mk exists already in gcc/ directory,
it sees that aarch64-cores.def is newer than aarch64-tune.md (unless
gen_update is used, that just touches aarch64-tune.md to make sure it
is newer) and regenerates it and as it is different, make install rebuilds
a large subset of the *.o files, but this time with the system g++
rather than previous stage one.  And during lto linking of it there
are differences in LTO bytecode between the compilers and we crash.

The following patch fixes that by regenerating aarch64-tune.md
(what was forgotten in r12-7842) and by adding a dependency from
s-mddeps to s-aarch64-tune-md, which makes sure that even when mddeps.mk
doesn't exist yet make sees the dependency and regenerates aarch64-tune.md
if needed.

2022-04-04  Jakub Jelinek  <jakub@redhat.com>

	PR target/105144
	* config/aarch64/t-aarch64 (s-mddeps): Depend on s-aarch64-tune-md.
	* config/aarch64/aarch64-tune.md: Regenerated.