Merge: Object destroy traces

- add destruction traces
- add lttng channel configuration file
- resolve the signed pointer issue by using uintptr_t instead of intptr_t
- resolve the discarded events issue by using a blocking channel mode.

To compile using the trace system: --trace

To test tracing some object instance and destroy events:
lttng load -i=~/nit/src/Nit_Compiler.lttng Nit_Compiler
lttng start
--> run your program
lttng stop

To read your CTF trace file:
babeltrace ~/lttng-traces/Nit_Compiler-.........

Signed-off-by: olivierschirm <olive.schirm@gmail.com>

Pull-Request: #2695
Reviewed-by: Alexis Laferrière <alexis.laf@xymus.net>
Reviewed-by: Jean Privat <jean@pryen.org>