lang: Handle empty translations wrt --no-warning

Do not emit empty translation warnings if --no-warning has been
specified.

We have a special handler for this case already (--warn-empty).

lang/lang-check.py

@@ -211,7 +211,7 @@ def check_translation(entry, msgids, is_pot, no_warning, no_suggest, warn_empty,
         return (errors == 0)
 
     # Missing translation
-    if len(translation) == 0 and (known_msgid or warn_empty):
+    if len(translation) == 0 and (warn_empty or (not no_warning and known_msgid)):
         errors += 1
         if rows == 1:
             print(yellow("[W]: Empty translation for \"%s\" on line %d" % (source, line)))