[libFuzzer] always install signal handler with SA_ONSTACK (#147422)

SA_ONSTACK is required for certain runtimes that use small stacks, for
instance the Go runtime.
See https://github.com/golang/go/issues/49075
SA_ONSTACK is a no-op unless someone also calls sigaltstack.

NOKEYCHECK=True
GitOrigin-RevId: aee4f2baccdbc018d0ac60eaa4e2a0a5f30bcdf5
1 file changed