Avoid a potential innocuous compiler warning.

Add a cast to avoid comparing a ssize_t value to a uint64_t value that
is always larger than a 32-bit ssize_t.  This silences an innocuous
compiler warning from e.g. gcc 4.2.1 about the comparison always having
the same result.

include/jemalloc/internal/nstime.h

@@ -7,7 +7,7 @@
 typedef struct nstime_s nstime_t;
 
 /* Maximum supported number of seconds (~584 years). */
-#define	NSTIME_SEC_MAX	18446744072
+#define	NSTIME_SEC_MAX	KQU(18446744072)
 
 #endif /* JEMALLOC_H_TYPES */
 /******************************************************************************/