[Xcb] update to libxcb 1.12 breaks 32bit applications

[Ran Benita]

On Wed, Jun 08, 2016 at 09:46:44PM +0200, G. Schlisio wrote:
> Am 08.06.2016 um 21:34 schrieb Rémi Cardona:
> > Does gcc's UBSan report anything? It could still very well be a bug in xcb.
> 
> never heard of it, sounds interesting.
> i compiled libxcb with gcc6 with -O2 and -fsanitize=undefined (thats
> what i understood from [0]) but there is no runtime error message.
> did i do it wrong?

I haven't read the code, but I also think gcc bug is not very likely
(though not impossible).

Can you try running the program under valgrind (without sanitizers).

To install, do `pacman -S valgrind`. Then, instead of `./my_program`,
run `valgrind ./my_program`.

There might be some noise, but I'd be interested in

- Whether it still crashes.
- Whether there's a report before the crash (or where the crash would
  have happened).

You can attach the valgrind output if there is any.

Ran