upgrade CRoaring to v2.0.2

[smmathews-brandwatch]

Upgrade to the latest version of CRoaring. As @acmcmurray points out, there are lots of bug fixes and general improvements.

In order to do this, three changes were necessary:

1. roaring.c and roaring.h were copied from https://github.com/RoaringBitmap/CRoaring/releases/tag/v2.0.2, without any changes.
2. The latest cstandard (c17) was set, which allows croaring to determine the atomic implementation.
3. Minor changes to the type/type-code were fixed up.
4. The old memory allocation code was changed to use croaring's memory hook system.

[acmcmurray]

I think this is definitely worth doing, the current version is from 2020 😮 -
I had a skim through, and there's lots of memory leak fixes, bug fixes and general improvements
RoaringBitmap/CRoaring@v0.2.66...v2.0.2 (if anyone else is interested)