* include/ruby/ruby.h, gc.c: rename macros and functions:
  OBJ_WB_GIVEUP() -> OBJ_WB_UNPROTECT(),
  rb_obj_wb_giveup() -> rb_obj_wb_unprotect(),
  rb_gc_giveup_promoted_writebarrier() ->
  rb_gc_writebarrier_unprotect_promoted(),
* class.c, eval.c, hash.c: use OBJ_WB_UNPROTECT().



git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@41582 b2dd03c8-39d4-4d8f-98ff-823fe69b080e