Method set_is_valid

BeefRT/gperftools/src/windows/patch_functions.cc:154–154

  bool patched() const { return is_valid(); }
  void set_is_valid(bool b) { is_valid_ = b; }
  // According to http://msdn.microsoft.com/en-us/library/ms684229(VS.85).aspx:
  // "The load address of a module (lpBaseOfDll) is the same as the HMODULE
  // value."