RFR (M): JDK-8020614: [TESTBUG] OutputAnalyzer.shouldHaveExitValue() should print stdout/stderr output

[Mikhailo Seledtsov]

This change adds reporting functionality to the JTREG test library. If 
error occurs during test run, the diagnostic summary will be printed 
consisting of a standard output, standard error and an exit code. The 
command line will be printed all the time, regardless of error encounter.

Webrev:
http://cr.openjdk.java.net/~mseledtsov/8020614/webrev.00/ 
<http://cr.openjdk.java.net/%7Emseledtsov/8020614/webrev.00/>

Bug:
https://jbs.oracle.com/bugs/browse/JDK-8020614

Thank you,
Misha