Move Parrot to C99 (subset)

[NotFound]

> Supporting C89 plus an enumerated subset of the C99 that MSVC supports sounds like a good idea, provided we don't lose support for any other useful compilers.  Let's list the needed features (snprintf and long long so far) and make sure they're supported by all of the compilers we want to be able to build Parrot with (gcc, msvc, icc, others?).  Any volunteers?

We don't need to require long long support from all compilers, just
being able to use it when available. There is no point in allowing
long long arguments for nci calls if the platforms don't support it,
for example.

-- 
Salu2