Workaround broken get_allow_undefined_link_args in DmdLikeCompilerMixin

Previously it worked by accident because BasicLinkerIsCompilerMixin had
that method misspelled.

mesonbuild/compilers/d.py

@@ -393,6 +393,9 @@ class DmdLikeCompilerMixin:
         # their own arguments
         return Compiler.get_soname_args(self, *args, **kwargs)
 
+    def get_allow_undefined_link_args(self) -> typing.List[str]:
+        return self.linker.get_allow_undefined_args()
+
 
 class DCompiler(Compiler):
     mscrt_args = {