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 <thanm@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>