test: add a test for gccgo bug #33062.
test: add a test for gccgo bug #33062.

Gccgo generates incorrect type equality functions for some types.
CL 185817 fixes it. This CL adds a test.

Updates #33062.

Change-Id: Id445c5d44a437512c65c46a029e49b7fc32e4d89
Reviewed-on: https://go-review.googlesource.com/c/go/+/185818
Run-TryBot: Cherry Zhang <d62e63aa42ce272d7b6a5055d97e942b33a34679@google.com>
Reviewed-by: Ian Lance Taylor <87e9c6d529889242b7e184afb632328636553ab4@golang.org>
TryBot-Result: Gobot Gobot <66cb808b70d30c07676d5e946fee83fd561249e5@golang.org>

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