RFR: JDK-8240555,,Using env of JAVA_TOOL_OPTIONS and _JAVA_OPTIONS breaks QuietOption.java test

[Jonathan Gibbons]

Please review a very simple fix to a javadoc test that fails when run 
with code coverage active.

The issue is that running with code coverage sets some environment 
variables, and the runtime noisily warns about the use of these 
environment variables. Suppressing the warnings is not an option.

The fix is to detect the warnings in the test, report a warning if they 
are found, and otherwise ignore them.

-- Jon

JBS: https://bugs.openjdk.java.net/browse/JDK-8240555
Webrev: file:///w/jjg/work/jdk.dev/8240555/webrev.00/index.html