RFR[XS] 8210040 [TESTBUG] TestOptionsWithRanges is very slow

[Ioi Lam]

https://bugs.openjdk.java.net/browse/JDK-8210040
http://cr.openjdk.java.net/~iklam/jdk12/8210040-TestOptionsWithRanges-slow.v01/

TestOptionsWithRanges spawns over 1000 JVM processes that try to force GC.
This scales very poorly on machines with lots of RAM. It timed out on my 
machine
with 64GB RAM after an hour.

The fix is to add -Xmx1024m to the command-line of the child processes. 
Also add
-XX:-ZapUnusedHeapArea for fastdebug builds.