Fix some issues found by cppcheck-1.58.

Some are real (although unlikely) bugs, others are just removal of
unnecessary code or stylistic changes. Fixes about 1/3 of the issues
this version of cppcheck finds; the remaining aren't as easily fixed and
most look like false positives.

Change-Id: Ic7ba3cc26be9906e037ecec9f8e63739ac3786be