uml: create arch.h

This patch moves the declarations of the architecture hooks from user_util.h
to a new header, arch.c, and adds the necessary includes to files which need
those declarations.

Signed-off-by: Jeff Dike <jdike@linux.intel.com>
Cc: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

arch/um/kernel/um_arch.c

@@ -28,6 +28,7 @@
 #include "asm/current.h"
 #include "user_util.h"
 #include "kern_util.h"
+#include "arch.h"
 #include "kern.h"
 #include "mem_user.h"
 #include "mem.h"