From: Matt Mackall <mpm@selenic.com>

This piece of the THREAD_SIZE cleanup got dropped.  If you make THREAD_SIZE
> 8k, the init thread overlaps the .init section and gets smashed.  I've
gone ahead and killed INIT_THREAD_SIZE throughout as it wasn't doing much.
This also saves 4k when we use 4k stacks.  Please apply.  Couple more minor
pieces remaining.