Allow (but ignore) Cached and Delegated volume options

These are only used on OS X Docker, and ignored elsewhere - but
since they are ignored, they're guaranteed to be safe everywhere,
and people are using them.

Fixes: #3340

Signed-off-by: Matthew Heon <matthew.heon@pm.me>

pkg/util/mountOpts.go

@@ -20,26 +20,22 @@ func ProcessOptions(options []string) []string {
 		foundbind, foundrw, foundro bool
 		rootProp                    string
 	)
+
 	for _, opt := range options {
 		switch opt {
 		case "bind", "rbind":
 			foundbind = true
-			break
+		case "ro":
+			foundro = true
+		case "rw":
+			foundrw = true
+		case "private", "rprivate", "slave", "rslave", "shared", "rshared":
+			rootProp = opt
 		}
 	}
 	if !foundbind {
 		options = append(options, "rbind")
 	}
-	for _, opt := range options {
-		switch opt {
-		case "rw":
-			foundrw = true
-		case "ro":
-			foundro = true
-		case "private", "rprivate", "slave", "rslave", "shared", "rshared":
-			rootProp = opt
-		}
-	}
 	if !foundrw && !foundro {
 		options = append(options, "rw")
 	}