sdk: replace sub() with saturating_sub()

sdk/program/src/program_stubs.rs

@@ -223,15 +223,14 @@ pub(crate) fn sol_get_epoch_rewards_sysvar(var_addr: *mut u8) -> u64 {
 #[doc(hidden)]
 pub fn is_nonoverlapping<N>(src: N, src_len: N, dst: N, dst_len: N) -> bool
 where
-    N: Ord + std::ops::Sub<Output = N>,
-    <N as std::ops::Sub>::Output: Ord,
+    N: Ord + num_traits::SaturatingSub,
 {
     // If the absolute distance between the ptrs is at least as big as the size of the other,
     // they do not overlap.
     if src > dst {
-        src - dst >= dst_len
+        src.saturating_sub(&dst) >= dst_len
     } else {
-        dst - src >= src_len
+        dst.saturating_sub(&src) >= src_len
     }
 }