cmd/internal/obj: exclude external test packages from FIPS scope
Excluding external test packages allows them to use
//go:embed, which requires data relocations in data.
(Obviously the external test code is testing the FIPS module,
not part of it, so this is reasonable.)
Change-Id: I4bae71320ccb5faf718c045540a9ba6dd93e378f
Reviewed-on: https://go-review.googlesource.com/c/go/+/628735
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com> Reviewed-by: Cherry Mui <cherryyz@google.com>