[hash] Use unsigned types

Hopefully ubsan wouldn't complain about overflows now.

src/hb-algs.hh

@@ -321,10 +321,10 @@ struct
   // https://github.com/harfbuzz/harfbuzz/pull/4228#issuecomment-1565079537
   template <typename T,
 	    hb_enable_if (std::is_integral<T>::value && sizeof (T) <= sizeof (uint32_t))> constexpr auto
-  impl (const T& v, hb_priority<1>) const HB_RETURN (uint32_t, v * 2654435761 /* Knuh's multiplicative hash */)
+  impl (const T& v, hb_priority<1>) const HB_RETURN (uint32_t, v * 2654435761u /* Knuh's multiplicative hash */)
   template <typename T,
 	    hb_enable_if (std::is_integral<T>::value && sizeof (T) > sizeof (uint32_t))> constexpr auto
-  impl (const T& v, hb_priority<1>) const HB_RETURN (uint32_t, (v ^ (v >> 32)) * 2654435761 /* Knuth's multiplicative hash */)
+  impl (const T& v, hb_priority<1>) const HB_RETURN (uint32_t, (v ^ (v >> 32)) * 2654435761u /* Knuth's multiplicative hash */)
 
   template <typename T> constexpr auto
   impl (const T& v, hb_priority<0>) const HB_RETURN (uint32_t, std::hash<hb_decay<decltype (hb_deref (v))>>{} (hb_deref (v)))