gc.c: speed up RGENGC_CHECK_MODE by removing unncessary check
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@44114 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
gc.c: speed up RGENGC_CHECK_MODE by removing unncessary check
after r44113
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@44114 b2dd03c8-39d4-4d8f-98ff-823fe69b080e