syscall: disable TestAllThreadsSyscall on linux-ppc64

For some reason, currently unknown, this test case fails exclusively
on the linux-ppc64 platform. Until such time as it can be made to
work, we'll disable this test case on that platform.

The same issue causes TestSetuidEtc to fail too, so disable that
on this platform.

Updates #42178

Change-Id: Idd3f6c2ee9f2fba2eb8ce4de69de7f316858bb15
Reviewed-on: https://go-review.googlesource.com/c/go/+/264719
Trust: Emmanuel Odeke <[email protected]>
Run-TryBot: Emmanuel Odeke <[email protected]>
TryBot-Result: Go Bot <[email protected]>
Reviewed-by: Ian Lance Taylor <[email protected]>

Author: AndrewGMorgan

src/syscall/syscall_linux_test.go

@@ -410,6 +410,9 @@ const (
 // syscalls that execute on all OSThreads - with which to support
 // POSIX semantics for security state changes.
 func TestAllThreadsSyscall(t *testing.T) {
+	if runtime.GOARCH == "ppc64" {
+		t.Skip("skipping on linux/ppc64; see issue #42178")
+	}
 	if _, _, err := syscall.AllThreadsSyscall(syscall.SYS_PRCTL, PR_SET_KEEPCAPS, 0, 0); err == syscall.ENOTSUP {
 		t.Skip("AllThreadsSyscall disabled with cgo")
 	}
@@ -577,6 +580,9 @@ func compareStatus(filter, expect string) error {
 // the syscalls. Care should be taken to mirror any enhancements to
 // this test here in that file too.
 func TestSetuidEtc(t *testing.T) {
+	if runtime.GOARCH == "ppc64" {
+		t.Skip("skipping on linux/ppc64; see issue #42178")
+	}
 	if syscall.Getuid() != 0 {
 		t.Skip("skipping root only test")
 	}