Describe the bug
A double free is thrown if a TCODPath is moved.

To Reproduce

{
  TCODPath a(1, 1, nullptr, nullptr);
  TCODPath b(std::move(a));
}

Expected behavior
No crash.

Environment (please complete the following information):

• Platform: WSL
• Libtcod version: 1.24.0
• Libtcod source: Vcpkg
• Compiler used: GCC