Ahaggar: add the xinstrument.h header file

Signed-off-by: Djalal Harouni <tixxdz@opendz.org>
Ahaggar: add the xinstrument-calls.h file

This files contains some call sites and the related instrumentation
helpers.

Signed-off-by: Djalal Harouni <tixxdz@opendz.org>