https://gcc.gnu.org/bugzilla/show_bug.cgi?id=116642
--- Comment #3 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
(From POSIX.1) The vfork() function has the same effect as
fork(2), except that the behavior is undefined if the process
created by vfork() either modifies any data other than a variable
of type pid_t used to store the return value from vfork(), or
returns from the function in which vfork() was called, or calls
any other function before successfully calling _exit(2) or one of
the exec(3) family of functions.
I think this code is undefined ...
