RFR 9: 8035889: jdk testlibrary - add printing of values of failed assertions

[roger riggs]

The testlibrary for the jdk should be printing the values in the failed
assertions to make debugging easier and quicker.

The webrev adds the printing of the failed assertions and added methods
for formatting and unconditional fail methods.

Webrev:
http://cr.openjdk.java.net/~rriggs/webrev-testlibrary-asserts-8035889/

Bug:
    8035889: jdk testlibrary - add printing of values of failed assertions

Thanks, Roger

[1] https://bugs.openjdk.java.net/browse/JDK-8035889