disambiguate hash usage (#1182)

Author: kripken

src/literal.h

@@ -158,8 +158,8 @@ namespace std {
 template<> struct hash<wasm::Literal> {
   size_t operator()(const wasm::Literal& a) const {
     return wasm::rehash(
-      hash<size_t>()(size_t(a.type)),
-      hash<int64_t>()(a.getBits())
+      uint64_t(hash<size_t>()(size_t(a.type))),
+      uint64_t(hash<int64_t>()(a.getBits()))
     );
   }
 };

src/support/hash.h

@@ -35,7 +35,7 @@ inline uint32_t rehash(uint32_t x, uint32_t y) { // see http://www.cse.yorku.ca/
   return hash;
 }
 
-inline size_t rehash(uint64_t x, uint64_t y) { // see boost and https://stackoverflow.com/a/2595226/1176841
+inline uint64_t rehash(uint64_t x, uint64_t y) { // see boost and https://stackoverflow.com/a/2595226/1176841
   return x ^ (y + 0x9e3779b9 + (x << 6) + (x >> 2));
 }