[asan] Change shadow type from unsigned to signed

[Xinliang David Li]

The following is small bug fix caught during testing. The shadow value
for redzone can be negative, so the shadow type must be signed for the
check to succeed.

Ok for the branch?

thanks,

David


Index: asan.c
===================================================================
--- asan.c      (revision 192567)
+++ asan.c      (working copy)
@@ -825,10 +825,10 @@ static void
 asan_init_shadow_ptr_types (void)
 {
   asan_shadow_set = new_alias_set ();
-  shadow_ptr_types[0] = build_distinct_type_copy (unsigned_char_type_node);
+  shadow_ptr_types[0] = build_distinct_type_copy (signed_char_type_node);
   TYPE_ALIAS_SET (shadow_ptr_types[0]) = asan_shadow_set;
   shadow_ptr_types[0] = build_pointer_type (shadow_ptr_types[0]);
-  shadow_ptr_types[1] = build_distinct_type_copy (short_unsigned_type_node);
+  shadow_ptr_types[1] = build_distinct_type_copy (short_integer_type_node);
   TYPE_ALIAS_SET (shadow_ptr_types[1]) = asan_shadow_set;
   shadow_ptr_types[1] = build_pointer_type (shadow_ptr_types[1]);
 }