updated for version 7.3.1159
Problem:    The round() function is not always available. (Christ van
            Willegen)
Solution:   Use the solution from f_round().
diff --git a/src/ex_cmds2.c b/src/ex_cmds2.c
index 66b7e4e..353ae89 100644
--- a/src/ex_cmds2.c
+++ b/src/ex_cmds2.c
@@ -982,7 +982,7 @@
 	double usec = (tm->tv_sec * 1000000.0 + tm->tv_usec) / count;
 
 	tm2->tv_sec = floor(usec / 1000000.0);
-	tm2->tv_usec = round(usec - (tm2->tv_sec * 1000000.0));
+	tm2->tv_usec = vim_round(usec - (tm2->tv_sec * 1000000.0));
 # endif
     }
 }