Trim all trailing whitespace

The `.editorconfig` file in this repo is configured to trim all trailing
whitespace regardless of whether the line is modified.

Trims all trailing whitespace in the repository to make the codebase easier
to work with in editors that respect `.editorconfig`.

`git blame` becomes less useful on these lines but it already isn't very useful.

Commands:

```
find . -type f -name '*.h' -exec sed --in-place 's/[[:space:]]\+$//' {} \+
find . -type f -name '*.c' -exec sed --in-place 's/[[:space:]]\+$//' {} \+
```

public/crclib.c

@@ -281,7 +281,7 @@ void MD5Update( MD5Context_t *ctx, const byte *buf, uint len )
 ===============
 MD5Final
 
-Final wrapup - pad to 64-byte boundary with the bit pattern 
+Final wrapup - pad to 64-byte boundary with the bit pattern
 1 0* (64-bit count of bits processed, MSB-first)
 ===============
 */