RFR(XS) : 8171097 : Convert TestReservedSpace_test to Gtest

[Igor Ignatyev]

http://cr.openjdk.java.net/~iignatyev//8171097/webrev.00/index.html
> 188 lines changed: 187 ins; 1 del; 0 mod; 

Hi all,

could you please review this small (and hopefully trivial) patch which converts internal TestReservedSpace_test to gtest? 
since 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.

webrev: http://cr.openjdk.java.net/~iignatyev//8171097/webrev.00/index.html
JBS: https://bugs.openjdk.java.net/browse/JDK-8171097
testing:
- converted tests on linux-x64, windows-x64, macosx-x64, solaris-sparcv9 in product and fastdebug variants 
- build w/ precompiled-headers enabled and disabled

PS the patch has been originally created by Kirill Zh, but hasn't been sent out for official review

Thanks,
-- Igor