Move list types from <linux/list.h> to <linux/types.h>.

This allows a list_head (or hlist_head, etc.) to be used from places
that used to be impractical, in particular <asm/processor.h>, which
used to cause include file recursion: <linux/list.h> includes
<linux/prefetch.h>, which always includes <asm/processor.h> for the
prefetch macros, as well as <asm/system.h>, which often includes
<asm/processor.h> directly or indirectly.

This avoids a lot of painful workaround hackery on the tile
architecture, where we use a list_head in the thread_struct to chain
together tasks that are activated on a particular hardwall.

Signed-off-by: Chris Metcalf <[e-mail]>
Reviewed-by: Matthew Wilcox <[e-mail]>

include/linux/list.h

···
 #ifndef _LINUX_LIST_H
 #define _LINUX_LIST_H
 
+#include <linux/types.h>
 #include <linux/stddef.h>
 #include <linux/poison.h>
 #include <linux/prefetch.h>
···
  * generate better code by using them directly rather than
  * using the generic single-entry routines.
  */
-
-struct list_head {
-	struct list_head *next, *prev;
-};
 
 #define LIST_HEAD_INIT(name) { &(name), &(name) }
 
···
  * too wasteful.
  * You lose the ability to access the tail in O(1).
  */
-
-struct hlist_head {
-	struct hlist_node *first;
-};
-
-struct hlist_node {
-	struct hlist_node *next, **pprev;
-};
 
 #define HLIST_HEAD_INIT { .first = NULL }
 #define HLIST_HEAD(name) struct hlist_head name = {  .first = NULL }

include/linux/types.h

···
 } atomic64_t;
 #endif
 
+struct list_head {
+	struct list_head *next, *prev;
+};
+
+struct hlist_head {
+	struct hlist_node *first;
+};
+
+struct hlist_node {
+	struct hlist_node *next, **pprev;
+};
+
 struct ustat {
 	__kernel_daddr_t	f_tfree;
 	__kernel_ino_t		f_tinode;