Fix non-list used with FeatureNewKwargs

The type of this argument needs checking, or single strings need handling correctly.

mesonbuild/build.py

@@ -1091,7 +1091,7 @@ recommended as it can lead to undefined behaviour on some platforms''')
                 return
 
 class Generator:
-    @FeatureNewKwargs('generator', '0.43.0', 'capture')
+    @FeatureNewKwargs('generator', '0.43.0', ['capture'])
     def __init__(self, args, kwargs):
         if len(args) != 1:
             raise InvalidArguments('Generator requires exactly one positional argument: the executable')

mesonbuild/interpreter.py

@@ -2832,7 +2832,7 @@ root and issuing %s.
                  mlog.bold(subproj_path), 'found:', mlog.green('YES'))
         return dep
 
-    @FeatureNewKwargs('executable', '0.42.0', 'implib')
+    @FeatureNewKwargs('executable', '0.42.0', ['implib'])
     @permittedKwargs(permitted_kwargs['executable'])
     def func_executable(self, node, args, kwargs):
         return self.build_target(node, args, kwargs, ExecutableHolder)