[MINOR] add curr_sec_ms and curr_sec_ms_scaled for current second.

Several algorithms will need to know the millisecond value within
the current second. Instead of doing a divide every time it is needed,
it's better to compute it when it changes, which is when now and now_ms
are recomputed.

curr_sec_ms_scaled is the same multiplied by 2^32/1000, which will be
useful to compute some ratios based on the position within last second.
diff --git a/include/common/time.h b/include/common/time.h
index 07d3070..abc1ccf 100644
--- a/include/common/time.h
+++ b/include/common/time.h
@@ -54,6 +54,8 @@
 #define MINTIME(old, new)	(((new)<0)?(old):(((old)<0||(new)<(old))?(new):(old)))
 #define SETNOW(a)		(*a=now)
 
+extern unsigned int   curr_sec_ms;      /* millisecond of current second (0..999) */
+extern unsigned int   curr_sec_ms_scaled;  /* millisecond of current second (0..2^32-1) */
 extern unsigned int   now_ms;           /* internal date in milliseconds (may wrap) */
 extern struct timeval now;              /* internal date is a monotonic function of real clock */
 extern struct timeval date;             /* the real current date */