optinterpreter: Add type annotations to is_invalid_name

mesonbuild/optinterpreter.py

@@ -24,7 +24,7 @@ forbidden_option_names = set(coredata.builtin_options.keys())
 forbidden_prefixes = [lang + '_' for lang in compilers.all_languages] + ['b_', 'backend_']
 reserved_prefixes = ['cross_']
 
-def is_invalid_name(name):
+def is_invalid_name(name: str) -> bool:
     if name in forbidden_option_names:
         return True
     pref = name.split('_')[0] + '_'