8160399: is_oop_or_null involves undefined behavior
8164984: Improper use of is_oop in production code
Summary: replace oop->is_oop*() with oopDesc::is_oop*(oop) so this pointer can be verified
Reviewed-by: iklam, kvn, dholmes

8181449: Fix debug.hpp / globalDefinitions.hpp dependency inversion
Summary: Refactor debug.hpp and reverse include dependency.
Reviewed-by: coleenp, stefank, dcubed

8178836: Improve PtrQueue index abstraction
Summary: Prefer element indexes where possible.
Reviewed-by: shade, mgerdin

8150676: Use BufferNode index
Summary: Maintain index and use it, removing extra checks for or stores of NULL.
Reviewed-by: jmasa, tschatzl

8149541: Use log_error() instead of log_info() when verification reports a problem
Reviewed-by: jwilhelm, tbenson

8145092: Use Unified Logging for the GC logging
Summary: JEP-271. VM changes contributed by brutisso, test changes contributed by david.
Reviewed-by: sjohanss, david, brutisso
Contributed-by: bengt.rutisson@oracle.com, david.lindholm@oralce.com

8077571: ObjPtrQueue is poorly named
Summary: Renamed to SATBMarkQueue and renamed files.
Reviewed-by: brutisso, tschatzl, dholmes, twisti