RFR 8185496: Improve performance of system properties initialization in initPhase1

[Roger Riggs]

While working to reduce startup time initializing properties, a pair of 
improvements are proposed.

8185496: Improve performance of system properties initialization in 
initPhase1 [1]
8213424: VersionProps duplicate initialization [2]

1) The overhead of providing default values in native is reduced by 
applying the defaults
     when first used and leaving the properties undefined unless there is
     an OS supplied value or a -D command line argument
2) Two tests for properties are combined into a more complete test

webrev:

http://cr.openjdk.java.net/~rriggs/webrev-props-cleanup-8185496/

Issues:
[1] https://bugs.openjdk.java.net/browse/JDK-8185496
[2] https://bugs.openjdk.java.net/browse/JDK-8213424

Thanks for any comments and suggestions, Roger