Userspace guest address offsetting

Re-implement GUEST_BASE support.
Offset guest ddress space by default if the guest binary contains
regions below the host mmap_min_addr.
Implement support for i386, x86-64 and arm hosts.

Signed-off-by: Riku Voipio <riku.voipio@iki.fi>
Signed-off-by: Paul Brook <paul@codesourcery.com>
diff --git a/linux-user/qemu.h b/linux-user/qemu.h
index 83ad443..8e728a3 100644
--- a/linux-user/qemu.h
+++ b/linux-user/qemu.h
@@ -133,6 +133,9 @@
 void task_settid(TaskState *);
 void stop_all_tasks(void);
 extern const char *qemu_uname_release;
+#if defined(CONFIG_USE_GUEST_BASE)
+extern unsigned long mmap_min_addr;
+#endif
 
 /* ??? See if we can avoid exposing so much of the loader internals.  */
 /*