sched/headers: Remove <linux/cgroup-defs.h> from <linux/sched.h>

It's not used by anything in <linux/sched.h> anymore.

This reduces the preprocessed size of <linux/sched.h> and
speeds up the build a bit.

Also fix code that implicitly relied on headers included by <linux/cgroup-defs.h>.
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>
Signed-off-by: Ingo Molnar <mingo@kernel.org>

include/linux/sched.h

@@ -28,7 +28,6 @@
 #include <linux/gfp.h>
 #include <linux/topology.h>
 #include <linux/magic.h>
-#include <linux/cgroup-defs.h>
 
 #include <asm/current.h>
 

include/target/target_core_base.h

@@ -4,6 +4,7 @@
 #include <linux/configfs.h>      /* struct config_group */
 #include <linux/dma-direction.h> /* enum dma_data_direction */
 #include <linux/percpu_ida.h>    /* struct percpu_ida */
+#include <linux/percpu-refcount.h>
 #include <linux/semaphore.h>     /* struct semaphore */
 #include <linux/completion.h>