8146987: Improve Parallel GC Full GC by caching results of live_words_in_range()
Summary: A large part of time in the parallel scavenge collector is spent finding out the amount of live words within memory ranges to find out where to move an object to. Try to incrementally calculate this value.
Reviewed-by: tschatzl, mgerdin, jmasa
Contributed-by: ray alex <sky1young@gmail.com>

8146395: Add inline qualifier in oop.hpp and fix inlining in gc files
Summary: Fix remaining issues after 8146401. Also fix windows VS2010 linkage problem (g1OopClosures.hpp).
Reviewed-by: stefank, mgerdin

8079792: GC directory structure cleanup
Reviewed-by: brutisso, stefank, david