RFR: 8230781: Add JTREG_FAILURE_HANDLER_TIMEOUT to control timeout handler timeout

[Leonid Mesnik]

Hi

Could you please review following fix which add 
JTREG_FAILURE_HANDLER_TIMEOUT option to customize timeout handler timeout.

webrev: http://cr.openjdk.java.net/~lmesnik/8230781/webrev.00/

bug: https://bugs.openjdk.java.net/browse/JDK-8230781

I verified fix locally and with mach5.

Leonid