~exec64/freekdl

Remove inline keyword, unrecognised by clang
Fix -pedantic build

Until now, freekdl has been building without the -pedantic flag which
caused gcc and clang not to respect some of the rules of ANSI C. I was
mistakenly using features not available yet. This change fixes that.
Add sourcehut build badge to README
Add source hut CI
Fix issues found by -Wall -Wextra
Remove use of min() macro in tests
FreeKDL initial public release