Changes

Add snprintf_os
 (commit: a9f7d74)

Rewrite the instrumented runtime to store traces in the CTF format.

The instrumentation code in the instrumented runtime was replaced
with new APIs to gather runtime statistics and output them in a new format
(Common Trace Format).
This commit also exposes new functions in the Gc module to pause or resume
instrumentation during a program execution (Gc.eventlog_pause and
Gc.eventlog_resume).
 (commit: b7f0494)