Move Slotinfo values into Images struct

So that this can be stored in its own structure, make it own the slot
info (which is only two usize values).

Signed-off-by: David Brown <david.brown@linaro.org>
diff --git a/sim/src/lib.rs b/sim/src/lib.rs
index 6ac796a..3f3967d 100644
--- a/sim/src/lib.rs
+++ b/sim/src/lib.rs
@@ -206,8 +206,8 @@
         // upgraded to
         let mut bad_flash = flash.clone();
         let bad_slot1_image = Images {
-            slot0: &slot0,
-            slot1: &slot1,
+            slot0: slot0.clone(),
+            slot1: slot1.clone(),
             primary: install_image(&mut bad_flash, slot0_base, 32784, false),
             upgrade: install_image(&mut bad_flash, slot1_base, 41928, true),
         };
@@ -215,8 +215,8 @@
         failed |= run_signfail_upgrade(&bad_flash, &areadesc, &bad_slot1_image);
 
         let images = Images {
-            slot0: &slot0,
-            slot1: &slot1,
+            slot0: slot0.clone(),
+            slot1: slot1.clone(),
             primary: install_image(&mut flash, slot0_base, 32784, false),
             upgrade: install_image(&mut flash, slot1_base, 41928, false),
         };
@@ -943,14 +943,15 @@
     build_num: u32,
 }
 
+#[derive(Clone)]
 struct SlotInfo {
     base_off: usize,
     trailer_off: usize,
 }
 
-struct Images<'a> {
-    slot0: &'a SlotInfo,
-    slot1: &'a SlotInfo,
+struct Images {
+    slot0: SlotInfo,
+    slot1: SlotInfo,
     primary: Vec<u8>,
     upgrade: Vec<u8>,
 }