test/threaded_execve: fix on metag

The metag ABI has stacks growing upwards so clone expects the stack
argument to point at the bottom of the stack instead of the top.

* test/threaded_execve.c [__metag__]: Define clone2 differently
to avoid a segfault at runtime.

Signed-off-by: James Hogan <james.hogan@imgtec.com>
1 file changed