iseq.h: check range

* iseq.h (iseq_catch_table_bytes): check range and suppress a
  warning.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@46854 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
* 2014-07-18

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@46855 b2dd03c8-39d4-4d8f-98ff-823fe69b080e