sched/deadline: Use C bitfields for the state flags

Ask the compiler to use a single bit for storing true / false values,
instead of wasting the size of a whole int value.
Tested with gcc 5.4.0 on x86_64, and the compiler produces the expected
Assembly (similar to the Assembly code generated when explicitly accessing
the bits with bitmasks, "&" and "|").

Signed-off-by: luca abeni <[email protected]>
Signed-off-by: Peter Zijlstra (Intel) <[email protected]>
Reviewed-by: Daniel Bristot de Oliveira <[email protected]>
Cc: Juri Lelli <[email protected]>
Cc: Linus Torvalds <[email protected]>
Cc: Mathieu Poirier <[email protected]>
Cc: Mike Galbraith <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Steven Rostedt <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Ingo Molnar <[email protected]>

Author: luca abeni

include/linux/sched.h

@@ -474,10 +474,10 @@ struct sched_dl_entity {
 	 * conditions between the inactive timer handler and the wakeup
 	 * code.
 	 */
-	int				dl_throttled;
-	int				dl_boosted;
-	int				dl_yielded;
-	int				dl_non_contending;
+	int				dl_throttled      : 1;
+	int				dl_boosted        : 1;
+	int				dl_yielded        : 1;
+	int				dl_non_contending : 1;
 
 	/*
 	 * Bandwidth enforcement timer. Each -deadline task has its