virt-aa-helper: /etc/libvirt-sandbox/services isn't restricted

To get virt-sandbox-service working with AppArmor, virt-aa-helper
needs not to choke on path in /etc/libvirt-sandbox/services.

src/security/virt-aa-helper.c

@@ -571,7 +571,8 @@ valid_path(const char *path, const bool readonly)
     };
     /* override the above with these */
     const char * const override[] = {
-        "/sys/devices/pci"	/* for hostdev pci devices */
+        "/sys/devices/pci",	/* for hostdev pci devices */
+        "/etc/libvirt-sandbox/services/" /* for virt-sandbox service config */
     };
 
     if (path == NULL) {