merge revision(s) 55663: [Backport #12583]
* gc.c (gc_mark_roots): should mark the VM object itself to mark singleton class of the VM object. Before this patch, we only set mark bit for the VM object and invoke mark function separately. [Bug #12583] * test/ruby/test_gc.rb: add a test.
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/branches/ruby_2_3@55919 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
merge revision(s) 55663: [Backport #12583]
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/branches/ruby_2_3@55919 b2dd03c8-39d4-4d8f-98ff-823fe69b080e