Ahaggar: add internal declaration of __error() and __warning()

Signed-off-by: Djalal Harouni <tixxdz@opendz.org>
Ahaggar: define the __error() and __warning() functions

Signed-off-by: Djalal Harouni <tixxdz@opendz.org>
Ahaggar: make the callback matchers take a flag argument

Signed-off-by: Djalal Harouni <tixxdz@opendz.org>
Ahaggar: use the msg_extra field and remove useless declarations

* Dynamic matchers can store messages in the pm->msg_extra so just
  use it now
* Remove the __error() and __warning() functions declarations since
  they are defined now in the gcc-log.h header

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