meson: Adjust -fstack-protector use

meson: Adjust -fstack-protector use

Back in 2014, -fstack-protector was reported not to work on
aarch64, so fe881ae086ec disabled it on that target. OS-wise,
its use is currently limited to just Linux, FreeBSD and Windows.

Looking at the situation today, it seems that whatever issue was
affecting aarch64 a decade ago has been resolved; moreover,
macOS can also use the feature these days.

I haven't checked any of the other BSDs, but since the feature
works on FreeBSD it's pretty safe to assume that they can use
it too. If we get reports that it's not the case, we can always
further restrict its usage accordingly.

Best viewed with 'git show -w'.

Signed-off-by: Andrea Bolognani <abologna@redhat.com>
Reviewed-by: Ján Tomko <jtomko@redhat.com>