Add offline compiler

[vosen]

Expected outcome:
A new subproject in ZLUDA: a command line tool zoc.exe (ZLUDA offline compiler) that compiles PTX to the final binary and saves it to disk along with intermediate formats

Comments:

• It's a developer's tool, we don't expect it to be used by the end-users
• For consistency with related projects (https://github.com/vosen/ptx_tests) it should use bpaf for command line (https://crates.io/crates/bpaf)
• It should take PTX and emit
  • Pre-linked LLVM bitcode texts (.ll)
  • Post-linking LLVM bitcode text (.ll) (optional if difficult)
  • Final ELF binary (.elf)
  • Disassembly of the final ELF binary (.asm) (optional if difficult)
• For implementation, look at how ZLUDA uses comgr and refactor it to save intermediates