cmd/go: add test for gccgo name mangling crash
cmd/go: add test for gccgo name mangling crash

Updates #33871

Change-Id: I73b1513a89ad89126159ce03ee72b922cd01916c
Reviewed-on: https://go-review.googlesource.com/c/go/+/200837
Run-TryBot: Ian Lance Taylor <87e9c6d529889242b7e184afb632328636553ab4@golang.org>
Run-TryBot: Bryan C. Mills <1c8aad60184261ccede67f5c63a0d2a3bf3c9ff4@google.com>
Reviewed-by: Bryan C. Mills <1c8aad60184261ccede67f5c63a0d2a3bf3c9ff4@google.com>
Reviewed-by: Than McIntosh <4b2922593166fc595a9b1a408f34f5d3817fe9d2@google.com>
TryBot-Result: Gobot Gobot <66cb808b70d30c07676d5e946fee83fd561249e5@golang.org>

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