misc/cgo/test: skip Test9400 on Alpine
Alpine has a known issue where setgid clobbers the Go stack (#39857).
misc/cgo/test skips other tests that use setgid on Alpine, but not
this one. It's not clear to me why this test *used to* pass, but when
I refactored misc/cgo/test in CL 447355 it started failing.
Disable this test on Alpine, like the other setgid tests.
Change-Id: I2e646ef55e2201a4f0b377319d719a011ec847f0
Reviewed-on: https://go-review.googlesource.com/c/go/+/448355
TryBot-Result: Gopher Robot <gobot@golang.org>
Run-TryBot: Austin Clements <austin@google.com>
Reviewed-by: Cherry Mui <cherryyz@google.com>