Make sure DtoType has been run on the DType before assembling a call.

gen/tocall.cpp

@@ -186,6 +186,10 @@ DValue* DtoCallFunction(Loc& loc, Type* resulttype, DValue* fnval, Expressions*
     // the callee D type
     Type* calleeType = fnval->getType();
 
+    // if the type has not yet been processed, do so now
+    if (calleeType->ir.type == NULL)
+        DtoType(calleeType);
+
     // get func value if any
     DFuncValue* dfnval = fnval->isFunc();