This var is currently useless, as it's apparent from reading the code. Until
2.6.11 it was used in some code related to jail mode, in the same proc.:

        if(jail){
		while(!reading) sched_yield();
	}

jail mode has been dropped, together with that use, so let's finish dropping
this.

Also, remove some other useless definitions I met.
Acked-by: Jeff Dike <jdike@addtoit.com>
Signed-off-by: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>