RFR: 8246572: Always pass java.library.path when running micro benchmarks

[Claes Redestad]

Hi,

sponsoring this patch for Jorn, which ensures the -Djava.library.path
argument is always passed in when running microbenchmarks via make.

Bug:    https://bugs.openjdk.java.net/browse/JDK-8246572
Webrev: http://cr.openjdk.java.net/~redestad/8246572/open.00/

Testing: tier1 ongoing

Thanks!

/Claes