This simplify the code, would have prevented GPR#205 and prepare ground
for upcoming improved backtrace generation.
From: Frédéric Bour <frederic.bour@lakaban.net>
git-svn-id: http://caml.inria.fr/svn/ocaml/trunk@16367 f963ae5c-01c2-4b8c-9fe0-0dff7051ff02
And share backtrace.c between asmrun and byterun.
From: Frédéric Bour <frederic.bour@lakaban.net>
git-svn-id: http://caml.inria.fr/svn/ocaml/trunk@16365 f963ae5c-01c2-4b8c-9fe0-0dff7051ff02