make SysRq-T show all tasks again

show_state() (SysRq-T) developed the buggy habbit of not showing
TASK_RUNNING tasks.  This was due to the mistaken belief that state_filter
== -1 would be a pass-through filter - while in reality it did not let
TASK_RUNNING == 0 p->state values through.

Fix this by restoring the original '!state_filter means all tasks'
special-case i had in the original version.  Test-built and test-booted on
i686, SysRq-T now works as intended.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/kernel/sched.c b/kernel/sched.c
index b9a6837..960d7c5 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -4746,7 +4746,7 @@
 		 * console might take alot of time:
 		 */
 		touch_nmi_watchdog();
-		if (p->state & state_filter)
+		if (!state_filter || (p->state & state_filter))
 			show_task(p);
 	} while_each_thread(g, p);