Ruby

vm_insnhelper.c: check symbol proc to throw

• vm_insnhelper.c (vm_throw_start): check if the iseq is symbol
  proc, class definition should not be a symbol proc.
  [ruby-core:75856] [Bug #12462]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@55297 b2dd03c8-39d4-4d8f-98ff-823fe69b080e