backports: Add smp_acquire__after_ctrl_dep()

smp_acquire__after_ctrl_dep() was introduced in kernel 4.8 in upstream
Linux commit 33ac279677d ("locking/barriers: Introduce
smp_acquire__after_ctrl_dep()") and is used by backports lib-refcount.c
implementation now.

This just adds the default implementation to backports.

Signed-off-by: Hauke Mehrtens <hauke@hauke-m.de>
1 file changed