Fix oom tests on non Linux

Signed-off-by: Maksym Pavlenko <pavlenko.maksym@gmail.com>

sys/oom_unsupported.go

@@ -0,0 +1,40 @@
+// +build !linux
+
+/*
+   Copyright The containerd Authors.
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.
+*/
+
+package sys
+
+const (
+	// OOMScoreMaxKillable is not implemented on non Linux
+	OOMScoreMaxKillable = 0
+	// OOMScoreAdjMax is not implemented on non Linux
+	OOMScoreAdjMax = 0
+)
+
+// SetOOMScore sets the oom score for the process
+//
+// Not implemented on Windows
+func SetOOMScore(pid, score int) error {
+	return nil
+}
+
+// GetOOMScoreAdj gets the oom score for a process
+//
+// Not implemented on Windows
+func GetOOMScoreAdj(pid int) (int, error) {
+	return 0, nil
+}