Summary:
Change `-llair-output` to `-output`, for binary form, and
`-llair-txt-output` to `-llair-output`, for textual form. Also
correspondingly change `.llair` to `.bllair`, for binary, and
`.llair.txt` to `.llair` for text.
This improves command line argument completion, and makes `.llair` the
extension of the files most commonly interacted with.
Reviewed By: ngorogiannis
Differential Revision: D24951506
fbshipit-source-id: ad4c73ca2
Josh Berdine