Previously we included it with an `-include` compiler directive. But
that's not portable. And it's better to be explicit anyway.
Every .c file should have `include "config.h"` first thing.
Signed-off-by: Ran Benita <ran@unusedvar.com>
This requires (well, at least implemented by) casting away `const` which
is undefined behavior, and clang started to warn about it.
The micro optimization didn't save too many allocations, anyway.
Signed-off-by: Ran Benita <ran@unusedvar.com>