FWIW intptr_t and uintptr_t

[Joel Sherrill]

Hi

I was doing some investigation this week and noticed that both these types are optional in C99 and POSIX. We know gcc and llvm have them and checked on two (non Microsoft) closed source compilers. All supported it.

I had always taken then for granted as part of C99. I think they are universally supported or nearly so. So no problem to use. 

Just a warning to keep squirrelled away. I don't think we should change anything.
--joel