In the spirit of commit 8199908f, likely
typo originally.

Found by enabling -Wparentheses on clang 3.7 and running a manual audit.
To the best of my knowledge, no such instances remain.
Reviewed-by: Michael Niedermayer <michael@niedermayer.cc>
Signed-off-by: Ganesh Ajjanagadde <gajjanagadde@gmail.com>