verity: fix valgrind warnings in OddLeafCount

We don't clear the end bits (non-hash) of the last block. This results
in uninitialized bits being factored into the root hash. This causes
test flakiness.

Fix by memset all leaf blocks after allocation.

BUG=none
TEST=Ran OddLeafCount with valgrind.

Change-Id: I626f1ab386a67d0da8dcaff40d25245bfc747994

R=taysom@chromium.org,wad@chromium.org

Review URL: http://codereview.chromium.org/6726045
1 file changed