RFR(XS) 7902576: Lazy query for current JVM args in Runner

[Dmitry Chuyko]

Hello,

Please consider a small enhancement that allows Runner to run without 
ManagementPermission "monitor" in some modes.

If JVM or Benchmark JVM parameters are provided for forked run, 
ManagementFactory is not accessed. As we don't have Oprional, orElseGet 
and lambdas, there is a conditional operator by hasValue().

rfe: https://bugs.openjdk.java.net/browse/CODETOOLS-7902576
webrev: http://cr.openjdk.java.net/~dchuyko/7902576/webrev.00/

Testing: JMH tests, 'java -Djava.security.manager 
-Djava.security.policy=jmh-security-minimal-runner-noman.policy -jar 
micros-jdk8/target/micros-jdk8-1.0-SNAPSHOT.jar -f 1 -bm ss -jvmArgs "" 
FileRead' works, where jmh-security-minimal-runner-noman.policy is 
jmh-security-minimal-runner.policy without ManagementPermission 
"monitor" permission.

--Dmitry