RFR(S) : 8209807 : improve handling exception in requires.VMProps

[Igor Ignatyev]

http://cr.openjdk.java.net/~iignatyev//8209807/webrev.01/index.html
> 122 lines changed: 30 ins; 25 del; 67 mod;

Hi all,

could you please review this patch which makes use of newly introduced error state of @requires properties[*] in jtreg?

w/ this patch, we set a value w/ the well-known prefix in case any errors happen while we are getting property values. when jtreg sees this value, it set error statues to the test, which makes such cases more observable; simplifies root-cause analyze. and , arguably most importantly, jtreg now won't fail a whole test execution, and failure to get a property will affect only the tests which depend on that property.

webrev: http://cr.openjdk.java.net/~iignatyev//8209807/webrev.01/index.html
JBS: https://bugs.openjdk.java.net/browse/JDK-8209807
testing: tier[1-2] and manually verified that errors are reported when they should be and affect only certain tests  
 
[*] https://bugs.openjdk.java.net/browse/CODETOOLS-7902290

Thanks,
-- Igor