properties-window: Fix permission checkboxes needing two clicks with multiple files.

initial_permission_state_consistent() stored the full mode of the
first file but compared the other files against it after masking,
so with more than one file the initial state never looked
consistent. Enabling a permission checkbox then went to the
'mixed' state and restored the original permissions, and only the
second click actually applied the change.

Fixes #3641

src/nemo-properties-window.c

@@ -3428,7 +3428,7 @@ initial_permission_state_consistent (NemoPropertiesWindow *window,
 				return FALSE;
 			}
 
-			first_permissions = permissions;
+			first_permissions = permissions & mask;
 			first = FALSE;
 
 		} else if ((permissions & mask) != first_permissions) {