Allow unit tests on non-Linux OS

cmd/runmqserver/mqconfig_other.go

@@ -0,0 +1,9 @@
+// +build !linux
+
+package main
+
+// Dummy version of this function, only for non-Linux systems.
+// Having this allows unit tests to be run on other platforms (e.g. macOS)
+func checkFS(path string) {
+	return
+}