Fixes for timing and clang-tidy use.

[gdamore]

fixes #28 Timing calculations are wrong
fixes #29 TEST_CASE should evaluate as a statement (no trailing semicolon)

I've added my copyright as a "Portions" bit. If you prefer to instead just have me add a Copyright line below yours (how I do it for my repos), please let me know (or just make the change yourself).

Meaning, I'm also happy with:

 * Copyright (c) 2013-2019 Martin Mitas
 * Copyright 2019 Garrett D'Amore 
 *
 * ... license text follows

Oh, and thanks for your work on this project -- I'm now using it in NNG (as you know), and have begin replacing my own framework (c-convey -- see github.com/gdamore/c-convey) with it as this is simply easier to use and debug.

As an aside, the "(c)" in your copyright statement is actually useless (following a bad practice started by companies years ago who should have known better). Because (c) is not recognized as the copyright symbol, and even if it were, it is entirely redundant to the word "Copyright" in copyright law. (The symbol was intended for uses where a shorthand substitute for the word "Copyright" was desired.)

[mity]

I've added my copyright as a "Portions" bit. If you prefer to instead just have me add a Copyright line below yours (how I do it for my repos), please let me know (or just make the change yourself).

Yes please. That would be much better.

[gdamore]

I've added my copyright as a "Portions" bit. If you prefer to instead just have me add a Copyright line below yours (how I do it for my repos), please let me know (or just make the change yourself).

Yes please. That would be much better.

Done.

[mity]

Thanks for fixing all those. Generally, looks good to me.

I'm just wondering about the CLOCK_MONOTONIC_RAW change little bit, your comment in the issue makes me rather more confused because as far as I remember those two should be same except the adjustments.

[mity]

Merged. Thanks a lot for the fixes and the explanation.