check: prctl -- Add PR_SET_MM_AUXV test

The ability to set PR_SET_MM_AUXV is implemented
in kernel as a separate PR_SET_MM extension, so
we need to test if the kernel patch is applied
on a running system.

Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>