8027746: Remove do_gen_barrier template parameter in G1ParCopyClosure Summary: Remove the above mentioned template parameter and related unused code. Also remove some classes that are never used. Reviewed-by: stefank, mgerdin, jwilhelm

;
; This .DEF file is a placeholder for one which is automatically
; generated during the build process. See
; make\windows\build_vm_def.sh and
; make\windows\makefiles\projectcreator.make (esp. the "-prelink"
; options).
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