[Bug target/124586] aarch64-netbsd native build misses driver-aarch64.o for host_detect_local_cpu

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=124586

--- Comment #3 from Christopher Albert <albert at tugraz dot at> ---
Open for review, comments welcome:
https://github.com/lazy-fortran/gcc/pull/36

One-line fix: config.host adds aarch64*-*-netbsd* to the case pattern
that enables driver-aarch64.o and host_detect_local_cpu, so native
AArch64 NetBSD builds link the driver again and -mcpu=native works.
Companion to the PR95128 outline-atomics default (fork PR 35).
Verified with an aarch64--netbsd cross all-gcc build; host detection
failed to link before and passes after. x86_64 check-fortran is
unaffected.