RFR: 8153394: Add Unified Logging to make it easy to trace time taken in initPhase2

[Rachel Protacio]

Hello!

Please review this small change, adding unified logging for Phase2 
initialization, using the TraceTime class. (A jigsaw enhancement, which 
is why it's going in after FC.)

Bug: https://bugs.openjdk.java.net/browse/JDK-8153394
Open webrev: http://cr.openjdk.java.net/~rprotacio/8153394.00/

Output sample:

    $ java -Xlog:startuptime+modules -version
    [0.410s][info][modules,startuptime] Phase2 initialization, 0.1302802
    secs
    java version "9-internal"
    Java(TM) SE Runtime Environment (fastdebug build
    9-internal+0-2016-06-09-092114.rprotaci.8153394)
    Java HotSpot(TM) 64-Bit Server VM (fastdebug build
    9-internal+0-2016-06-09-092114.rprotaci.8153394, mixed mode)

Includes added conditions to logging/StartupTimeTest.java. Passes JPRT.

Thanks,
Rachel