mjit.c: fix deadlock on marking MJIT's ISeq
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@62549 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
mjit.c: fix deadlock on marking MJIT's ISeq
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@62549 b2dd03c8-39d4-4d8f-98ff-823fe69b080e