go-seccomp: fix TestInstall for Go 1.5.

In Go 1.5, os.Open() uses "openat" system call instead of "open".

BUG=chromium:489765
TEST=Ran 'go test -cpu=10 -test_install -test_endian' on host.
TEST=Cross compiled test with 'x86_64-cros-linux-gnu-go' and ran on a panther device.
TEST=Cross compiled test with 'i686-pc-linux-gnu-go' and ran on a x86-zgb device.
TEST=Cross compiled test with 'armv7a-cros-linux-gnueabi-go' and ran on a daisy device.

Change-Id: I357e3e8b78d83b3f743ed9c691dfa1d825418869
Reviewed-on: https://chromium-review.googlesource.com/303493
Commit-Ready: Rahul Chaudhry <rahulchaudhry@chromium.org>
Tested-by: Rahul Chaudhry <rahulchaudhry@chromium.org>
Reviewed-by: Matthew Dempsky <mdempsky@chromium.org>
Reviewed-by: Rahul Chaudhry <rahulchaudhry@chromium.org>
diff --git a/src/chromiumos/seccomp/seccomp_test.go b/src/chromiumos/seccomp/seccomp_test.go
index a5b90ab..2b86ea7 100644
--- a/src/chromiumos/seccomp/seccomp_test.go
+++ b/src/chromiumos/seccomp/seccomp_test.go
@@ -426,8 +426,9 @@
 	}
 
 	file := []string{
-		"# open: return EPERM",
+		"# open/openat: return EPERM",
 		"open: return 1",
+		"openat: return 1",
 		"# default: ALLOW",
 	}