fix for microsecond clock -- remove extra call to time which sometimes caused regression failures

[SVN r29181]

libs/date_time

@@ -1 +1 @@
-Subproject commit ea0e997bf50284f9bd13e029dcbaea75c75e94c2
+Subproject commit 394bb9911e6fbd66d979e6b4ba9e7383dad9c671