doc: Update control-dependencies section of memory-barriers.txt

This commit adds consistency to examples, formatting, and a couple of
additional warnings.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
This commit is contained in:
Paul E. McKenney 2016-12-13 16:42:32 -08:00
commit c8241f8553