This allows us to use the newest versions of linter tools.

This commit makes lots of changes to the C code to appease the
Clang-Tidy linter. Some of the less obvious ones are due to C's weird
semantics regarding handling of numeric literals.

We also disable a bunch of the detections because they are
super-pedantic, arguably useless, or we have our own unwritten coding
style rules that solve the issues.

this checks things such as inconsistent declarations and definitions

This supports linting of C code using clang-tidy to fix common
security and code quality issues early in the development workflow.
The benefit is that less time has to be spent in code reviews to
point out obvious problems, and ideally when the outstanding issues
are fixed, clang-tidy (and clang-format) can also be used to to
automatically fix basic problems and enforce common code style,
similarly to `go vet && go fmt` workflow.