Add configure check for which printf length modifiers are available

[Snaipe]

On the topic of shaving preprocessor branches, I think the simplest thing to do here, since we only expose these format specifiers through cr_asprintf which in turn uses whatever vsnprintf implementation is available, is to add a configure-time check for the "ll" and "z" length modifiers, as well as what PRI{u,d}64 means on the current platform. We can then define the right format specifiers in a config.h installed in criterion/.

I don't think I'll do that in this PR, but I'll open an issue to remember to do that later.

Originally posted by @Snaipe in https://github.com/Snaipe/Criterion/pull/324#issuecomment-570059848