Re-enable -Wall and -Werror that were lost in a merge

-Wall and -Werror were lost during a merge when they were added to
aaptCFLAGS instead of aaptCFlags.  Fix the typo, and the warnings
that crept in while it was disabled.

Change-Id: Ib944b8d6149278e4f3861c1acac277bcd95cc7c2