iseq.c: mark parent iseq
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@53524 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
iseq.c: mark parent iseq
generated iseq by eval from GC. [ruby-core:72620] [Bug #11928]
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@53524 b2dd03c8-39d4-4d8f-98ff-823fe69b080e