[knot-dns-users] zlib dependency

Knot DNS depends on zlib to calculate Adler-32 checksums. A comment in crc.h states that it “should be removed”. I want to use knsupdate on OpenWRT and would also like to remove the dependency. Unfortunately, there is no single library that provides only Adler-32 checksums and every examined software either relies on zlib or its bundled implementation of varying quality and speed. Other projects seem to use CRC32C because there is an instruction to calculate it in the SSE4.2 instruction set. But again there is no library that only implements only CRC32C checksums. Switching to CRC32C would also make the journal format incompatible. I'm inclined to just copy the reference implementation from RFC 1950 for my purposes but wanted to check with the upstream maintainers whether there are any plans or ideas. It would also be nice if the configure script would have an option to not include and compile unused functionality from libknot and libzscanner to minimize binaries sizes. - Matthias-Christian