[JFFS2] debug.h: include <linux/sched.h> for current->pid

Signed-off-by: David Woodhouse <dwmw2@infradead.org>

fs/jffs2/debug.h

@@ -13,6 +13,7 @@
 #ifndef _JFFS2_DEBUG_H_
 #define _JFFS2_DEBUG_H_
 
+#include <linux/sched.h>
 
 #ifndef CONFIG_JFFS2_FS_DEBUG
 #define CONFIG_JFFS2_FS_DEBUG 0