cmd/compile: add test for issue 37246
cmd/compile: add test for issue 37246

CL 233857 fixed the underlying issue for #37246,
which had arisen again as #38916.

Add the test case from #37246 to ensure it stays fixed.

Fixes #37246

Change-Id: If7fd75a096d2ce4364dc15509253c3882838161d
Reviewed-on: https://go-review.googlesource.com/c/go/+/233941
Run-TryBot: Josh Bleecher Snyder <cdc248cc4d32e4fbfe04e45228163bcecd48a0b9@gmail.com>
TryBot-Result: Gobot Gobot <66cb808b70d30c07676d5e946fee83fd561249e5@golang.org>
Reviewed-by: Michael Munday <19411bdeea90f848b8e02e9a1c63a7ce7cc699ea@ibm.com>

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