reflect: add embedded field test
reflect: add embedded field test

Gccgo failed this test.

Updates #23620

Change-Id: I3979a6d3b87d2d014850accf9cb7f356349e6195
Reviewed-on: https://go-review.googlesource.com/91138
Run-TryBot: Ian Lance Taylor <87e9c6d529889242b7e184afb632328636553ab4@golang.org>
TryBot-Result: Gobot Gobot <66cb808b70d30c07676d5e946fee83fd561249e5@golang.org>
Reviewed-by: Than McIntosh <4b2922593166fc595a9b1a408f34f5d3817fe9d2@google.com>

nawawi/go,cloudflare/go,akutz/go,josharian/go,josharian/go,cloudflare/go,cloudflare/go,akutz/go,CAFxX/go,nawawi/go,golang/go,nawawi/go,akutz/go,codestation/go,nawawi/go,akutz/go,cloudflare/go,golang/go,akutz/go,Cofyc/go,Cofyc/go,codestation/go,CAFxX/go,akutz/go,CAFxX/go,CAFxX/go,Cofyc/go,CAFxX/go,Cofyc/go,josharian/go,CAFxX/go,golang/go,cloudflare/go,codestation/go,cloudflare/go,nawawi/go,josharian/go,josharian/go,Cofyc/go,josharian/go,nawawi/go,CAFxX/go,nawawi/go,nawawi/go,codestation/go,codestation/go,codestation/go,cloudflare/go,golang/go,Cofyc/go,golang/go,akutz/go,josharian/go,golang/go,Cofyc/go,josharian/go,codestation/go,akutz/go,Cofyc/go,cloudflare/go,CAFxX/go,golang/go,codestation/go,golang/go