Update hash from MurmurHash2 to MurmurHash3.

Update hash from MurmurHash2 to MurmurHash3, primarily because the
latter generates 128 bits in a single call for no extra cost, which
simplifies integration with cuckoo hashing.

include/jemalloc/internal/jemalloc_internal.h.in

@@ -226,6 +226,7 @@ static const bool config_ivsalloc =
 #define	ALLOCM_LG_ALIGN_MASK	((int)0x3f)
 
 #define	ZU(z)	((size_t)z)
+#define	QU(q)	((uint64_t)q)
 
 #ifndef __DECONST
 #  define	__DECONST(type, var)	((type)(uintptr_t)(const void *)(var))