Add stubs for raw_input() input() and cmp()

I think these are getting accessed but not used right now

src/runtime/builtin_modules/builtins.cpp

@@ -990,6 +990,18 @@ Box* builtinIter(Box* obj, Box* sentinel) {
     return r;
 }
 
+Box* rawInput(Box* prompt) {
+    Py_FatalError("unimplemented");
+}
+
+Box* input(Box* prompt) {
+    Py_FatalError("unimplemented");
+}
+
+Box* builtinCmp(Box* lhs, Box* rhs) {
+    Py_FatalError("unimplemented");
+}
+
 void setupBuiltins() {
     builtins_module = createModule("__builtin__", "__builtin__");
 
@@ -1195,5 +1207,14 @@ void setupBuiltins() {
         "eval", new BoxedBuiltinFunctionOrMethod(boxRTFunction((void*)eval, UNKNOWN, 1, 0, false, false), "eval"));
     builtins_module->giveAttr("callable",
                               new BoxedBuiltinFunctionOrMethod(boxRTFunction((void*)callable, UNKNOWN, 1), "callable"));
+
+    builtins_module->giveAttr(
+        "raw_input", new BoxedBuiltinFunctionOrMethod(boxRTFunction((void*)rawInput, UNKNOWN, 1, 1, false, false),
+                                                      "raw_input", { NULL }));
+    builtins_module->giveAttr(
+        "input",
+        new BoxedBuiltinFunctionOrMethod(boxRTFunction((void*)input, UNKNOWN, 1, 1, false, false), "input", { NULL }));
+    builtins_module->giveAttr("cmp",
+                              new BoxedBuiltinFunctionOrMethod(boxRTFunction((void*)builtinCmp, UNKNOWN, 2), "cmp"));
 }
 }