* regexec.c (onig_search): fix problem with optimization of \z.
  [Backport #8210]
  patched by k_tanaka at [ruby-core:54251].


git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/branches/ruby_1_9_3@40713 b2dd03c8-39d4-4d8f-98ff-823fe69b080e