Add microsecond accuracy to log timestamps

This is useful while debugging and trying to check events across other
outputs such as pcap files, process logs, etc.

Change-Id: I43bb5c6e9977189251802bc2b078c52eb046bab8
diff --git a/selftest/process_test.ok.ign b/selftest/process_test.ok.ign
index 0abd7d5..b817f5a 100644
--- a/selftest/process_test.ok.ign
+++ b/selftest/process_test.ok.ign
@@ -1,7 +1,7 @@
 PATH='[^']*'	PATH=[$PATH]
 /tmp/[^/ '"]*	[TMP]
 pid=[0-9]*	pid=[PID]
-....-..-.._..:..:..	[DATETIME]
+....-..-.._..:..:..\.......	[DATETIME]
 '[^']*/selftest/process_test/foo.py'	[$0]
 "[^"]*/selftest/process_test/foo.py"	[$0]
 , line [0-9]*	, line [LINE]