Fix issues detected by Coverity Scan

Most of Coverity Scan reports are false
positives, but in rare cases we have
confirmed (very small) issues.

No functional change.
Speed up by almost 3%

This apparentely silly tweak allows
to speed up the bench by almost 3%.

Not clear why, repeating with perft,
the speed up vanishes.

Suggested by Jonathan Calovski.

No functional change.
Merge remote-tracking branch 'upstream/master'