Implement Eq and PartialOrd for CStrBuf
Implement Eq and PartialOrd for CStrBuf

The comparisons do not necessarily scan to the end of the string,
and in the worst case the strings need to be read all over
even if the lengths are equal. So the performance benefit of a
pre-computed length is not clear-cut there.

mzabaluev/rust-c-str