fix the type of CLOCKS_PER_SEC to match new clock_t type

originally it was right on 32-bit archs and wrong on 64-bit, but after
recent changes it was wrong everywhere. with this commit, it's now
right everywhere.

include/time.h

@@ -55,7 +55,7 @@ struct tm *localtime (const time_t *);
 char *asctime (const struct tm *);
 char *ctime (const time_t *);
 
-#define CLOCKS_PER_SEC 1000000UL
+#define CLOCKS_PER_SEC 1000000L
 
 
 #if defined(_POSIX_SOURCE) || defined(_POSIX_C_SOURCE) \