Portability part 1 - C99 printf

printf, sprintf, fprintf etc are now all C99 compliant. All except sprintf, which is now signaled as deprecated. This raises a few warnings about sprintf usage in the build. Some I fix with pull requests that will follow. Some others should be fixed by the respective authors.
Casting 0 in order to format it with %zu is kinda perverse.  Why not simply inline it, `s/:%zu:/:0:/` ?