RFR(S): 8164230: Convert TestCodeCacheRemSet_test to GTest

[Kirill Zhaldybin]

Dear all,

Could you please review this fix for 8164230?

Since we need CodeRootSetTable class to be declared in the test it was 
moved to new file src/share/vm/gc/g1/g1CodeCacheRemSet.internal.hpp.
This file is included by both test_g1CodeCacheRemSet.cpp and 
g1CodeCacheRemSet.cpp.

G1CodeRootSetTest is a friend class for G1CodeRootSet so we can get 
access to its internals.

CR: https://bugs.openjdk.java.net/browse/JDK-8164230
WebRev: http://cr.openjdk.java.net/~kzhaldyb/webrevs/JDK-8164230/webrev.00/

Thank you.

Regards, Kirill