Guard printing code of Compile::print_method in PRODUCT

In `Compile::print_method(CompilerPhaseType cpt, Node* n, int level)` the code
```
ResourceMark rm;
  stringStream ss;
  ss.print_raw(CompilerPhaseTypeHelper::to_string(cpt));
  if (n != NULL) {
    ss.print(": %d %s ", n->_idx, NodeClassNames[n->Opcode()]);
  } else {
    ss.print_raw(": NULL");
  }
```
needs to be guarded by a `#ifndef PRODUCT` since the usage of the string is also guarded in `Compile::print_method_impl`