RFR: 8073331: [TESTBUG] Test for VM option file feature (VM options specified in file)

[Dmitry Dmitriev]

Hello,

Please review a new test for recently added feature: JDK-8061999 
"Enhance VM option parsing to allow options to be specified in a file".  
Also, I need a sponsor for this fix.

This test verifies new "-XX:VMOptionsFile" VM Options. Several valid VM 
Options files are tested: with different number and types of options, 
empty file, file with only tab and spaces, file which contains 
properties with quotes. Also invalid situations are tested: not existing 
file, folder instead of the file, file with size greater than allowed, 
several VM option files and so on. Also, test verifies "last argument 
wins" situation: when the same option or property is defined several 
times in environment variables, on command line and in VM Options file. 
In this case option or property should get the last value from the most 
priority source. Here a priority of the sources(from less priority to 
the more priority):
1) Flags file
2) JAVA_TOOL_OPTIONS environment variables
3) Pseudo command line from launcher(which can include VM Options file)
4) _JAVA_OPTIONS

Webrev: http://cr.openjdk.java.net/~ddmitriev/8073331/webrev.00/
JBS: https://bugs.openjdk.java.net/browse/JDK-8073331
Feature JBS: https://bugs.openjdk.java.net/browse/JDK-8061999
Tested: JPRT with new test

Thank you,
Dmitry