Summary: stdint.h defines the modern standard c types which have a fixed memory size. This makes the program run more predictably as well as removing the need to ugly double work types such as `unsigned int` or `long long`.
Reviewed By: lucasr
Differential Revision: D3649096
fbshipit-source-id: dc9fc8861c3106494c5d00d6ac337da50a4c945b