Fix #928 - Fix hashing of negative 0.

Author: bakpakin

src/core/value.c

@@ -322,6 +322,7 @@ int32_t janet_hash(Janet x) {
                 uint64_t u;
             } as;
             as.d = janet_unwrap_number(x);
+            as.d = as.d == 0 ? 0 : as.d; /* normalize negative 0 */
             uint32_t lo = (uint32_t)(as.u & 0xFFFFFFFF);
             uint32_t hi = (uint32_t)(as.u >> 32);
             uint32_t hilo = (hi ^ lo) * 2654435769u;

test/suite0011.janet

@@ -48,5 +48,7 @@
 
 (assert (= (test) '(1 ())) "issue #919")
 
+(assert (= (hash 0) (hash (* -1 0))) "hash -0 same as hash 0")
+
 (end-suite)