insns.def (opt_regexpmatch2): respect redefined match op

* insns.def (opt_regexpmatch2): respect redefined match op
  Thanks to Sam Rawlins for the fix.
* test/ruby/test_string.rb: test based on Tsuyoshi Sawada's report
  [Bug #9581]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@45318 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
* 2014-03-12

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@45319 b2dd03c8-39d4-4d8f-98ff-823fe69b080e