V6 cc needs hash before whitespace before first include?

[Phil Budne]

> Anybody know what the story is there?

It's an indicator that the pre-processor needs to be run first.

The v6 code I've seen never used an include file for the stty/gtty
calls (as opposed to using a struct defined in an include file) so I'm
betting it was a speedup to not fork/exec another process if it was
going to be a null transform!