RFR(XXS) : 8177709 : Convert TestVirtualSpace_test to GTest

[Igor Ignatyev]

http://cr.openjdk.java.net/~iignatyev//8177709/webrev.00/index.html
> 141 lines changed: 140 ins; 1 del; 0 mod; 

Hi all,

could you please review this small (and hopefully trivial) patch which converts internal TestVirtualSpace_test to gtest? 
again, the old test is still used by WhiteBox::runMemoryUnitTests, the old code hasn't been removed. it will be removed later when all 4 tests used by runMemoryUnitTests are converted.

for the sake of reviewer, http://hg.openjdk.java.net/jdk/jdk/file/2e928420389d/src/hotspot/share/memory/virtualspace.cpp#l1261 is the old version.

webrev: http://cr.openjdk.java.net/~iignatyev//8177709/webrev.00/index.html
JBS: https://bugs.openjdk.java.net/browse/JDK-8177709
testing:
- converted tests on linux-x64, windows-x64, macosx-x64, solaris-sparcv9 in product and fastdebug variants 
- build w/ precompiled-headers enabled and disabled

Thanks,
-- Igor