We can be on v4.9 or newer kernel, but have no 32-bit multilib
toolchain, which will result in !CONFIG_COMPAT but
kdat_compat_sigreturn_test() will return true as we have
new arch_prctls in kernel needed for compatible C/R.
Fail compat test in this case.

travis-ci: success for 32-bit tests fixes
Reported-by: Andrei Vagin <avagin@virtuozzo.com>
Signed-off-by: Dmitry Safonov <dsafonov@virtuozzo.com>
Signed-off-by: Pavel Emelyanov <xemul@virtuozzo.com>
Signed-off-by: Andrei Vagin <avagin@virtuozzo.com>