cpupick: Move AvoidCPUs from util into cpupick as Avoid

cpupick/avoid_other.go

@@ -0,0 +1,8 @@
+//go:build !linux || android || e2e_testing
+
+package cpupick
+
+import "errors"
+
+// Avoid is unsupported outside Linux: there is no thread affinity API to restrict.
+func Avoid(_ []int, _ bool) error { return errors.ErrUnsupported }