cmd/link: fix imports problem in elf_test.go
cmd/link: fix imports problem in elf_test.go

Fix an imports problem in this test (doesn't compile).

Updates #35779

Change-Id: Icaeec0384bf2e75696e43d9410df7219f0245940
Reviewed-on: https://go-review.googlesource.com/c/go/+/210578
Run-TryBot: Than McIntosh <4b2922593166fc595a9b1a408f34f5d3817fe9d2@google.com>
Reviewed-by: Brad Fitzpatrick <ae9783c0b0efc69cd85ab025ddd17aa44cdc4aa5@golang.org>

nawawi/go,CAFxX/go,CAFxX/go,cloudflare/go,golang/go,cloudflare/go,akutz/go,cloudflare/go,cloudflare/go,golang/go,CAFxX/go,nawawi/go,cloudflare/go,CAFxX/go,akutz/go,golang/go,cloudflare/go,golang/go,nawawi/go,akutz/go,nawawi/go,akutz/go,CAFxX/go,golang/go,golang/go,akutz/go,CAFxX/go,CAFxX/go,golang/go,akutz/go,nawawi/go,nawawi/go,akutz/go,nawawi/go,cloudflare/go,golang/go,nawawi/go,cloudflare/go,CAFxX/go,akutz/go