Use list_head in binfmt handling

Switch single-linked binfmt formats list to usual list_head's.  This leads
to one-liners in register_binfmt() and unregister_binfmt().  The downside
is one pointer more in struct linux_binfmt.  This is not a problem, since
the set of registered binfmts on typical box is very small -- (ELF +
something distro enabled for you).

Test-booted, played with executable .txt files, modprobe/rmmod binfmt_misc.

Signed-off-by: Alexey Dobriyan <adobriyan@sw.ru>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/include/linux/binfmts.h b/include/linux/binfmts.h
index 91c8c07..6b834dc 100644
--- a/include/linux/binfmts.h
+++ b/include/linux/binfmts.h
@@ -63,7 +63,7 @@
  * linux accepts.
  */
 struct linux_binfmt {
-	struct linux_binfmt * next;
+	struct list_head lh;
 	struct module *module;
 	int (*load_binary)(struct linux_binprm *, struct  pt_regs * regs);
 	int (*load_shlib)(struct file *);