Update the CT Known Logs implementation to C++11

While adding some new code, some low-hanging cleanups
were noted. The comparison function was using the wrong
signature (int v bool), named not according to the style guide, and some preconditions could have been strengthened. Embrace the C++11 and lambda-fy it +
simplify it.

BUG=none
[email protected]
[email protected]

Review URL: https://codereview.chromium.org/1885563005

Cr-Commit-Position: refs/heads/master@{#387512}
6 files changed