Linker wrapper to produce `VELF` files

[zetanumbers]

Rely on rust-psp implementation while development. Use Microsoft DLLs-like structure.

[zetanumbers]

• Wrapped linker is not included, it should exist within user's environment. Use PSVITA_WRAP_LINKER environment variable to deduce which linker to wrap, otherwise rust-lld (subject to change);
• Linker should implement ld flavor, rely on ld flavor of the wrapped linker;
• Input libraries can be:
  • Static library (.a, .o);
  • Vita shared library (.vso);
• Produced file can be:
  • Relocatable object file (.o);
  • Vita shared library (.vso);
  • Vita executable (.vexe);
• Vita executable (.vexe) and vita shared library (.vso) are used to create SELF files;
• Vita shared library (.vso) is a zip file containing a public interface static library with nids, and optional implementation module;