Greg/trace allocation

[gregory38]

This PR contains 2 parts.

• a very basic system to trace C alloc/free call
• various C memory leak fixes.

I open the PR to discuss it a bit

• tracing system
  • do we want file or a small keyword. I did the latter initially, but it doesn't play nice with STB. So I added macro for STB. But we might want to ditch keyword and goes with __FILE__ macro for everyone.
  • So far the tracing system is very basic (and can potentially be enough for small test)
    • it would love a script to check the nb of free vs nb of alloc
    • maybe there are external lib that can be plugged that will handle the leak check for us at exit. I didn't investigate it. side note: running valgrind on a mix of Go/C/Lua doesn't seem to be useful (false positive, no trace symbol)
• memory leak
  • need careful review
  • need a test application (arsene doesn't stress lutro enough)

[gregory38]

Damn ! Sorry again. I really need to check the base commit more carefully.