go/internal/gccgoimporter: test fix for older gccgo versions
go/internal/gccgoimporter: test fix for older gccgo versions

Import test fix https://golang.org/cl/153831 from std lib
version (skips issue29198.go test for older versions of gccgo).

Updates golang/go#29198.

Change-Id: Iddd903068a73a307b1d19d93a7c03b1d00365022
Reviewed-on: https://go-review.googlesource.com/c/153870
Run-TryBot: Than McIntosh <4b2922593166fc595a9b1a408f34f5d3817fe9d2@google.com>
TryBot-Result: Gobot Gobot <66cb808b70d30c07676d5e946fee83fd561249e5@golang.org>
Reviewed-by: Ian Lance Taylor <87e9c6d529889242b7e184afb632328636553ab4@golang.org>

golang/tools,golang/tools,golang/tools,golang/tools,golang/tools