sched/headers: Prepare for new header dependencies before moving code to <linux/sched/clock.h>

We are going to split <linux/sched/clock.h> out of <linux/sched.h>, which
will have to be picked up from other headers and .c files.

Create a trivial placeholder <linux/sched/clock.h> file that just
maps to <linux/sched.h> to make this patch obviously correct and
bisectable.

Include the new header in the files that are going to need it.

Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>

kernel/locking/lockdep.c

@@ -28,6 +28,7 @@
 #define DISABLE_BRANCH_PROFILING
 #include <linux/mutex.h>
 #include <linux/sched.h>
+#include <linux/sched/clock.h>
 #include <linux/delay.h>
 #include <linux/module.h>
 #include <linux/proc_fs.h>

kernel/locking/qspinlock_stat.h

@@ -63,6 +63,7 @@ enum qlock_stats {
  */
 #include <linux/debugfs.h>
 #include <linux/sched.h>
+#include <linux/sched/clock.h>
 #include <linux/fs.h>
 
 static const char * const qstat_names[qstat_num + 1] = {