* vm.c (vm_exec): support :b_return event for "lambda{return}.call".
  [Bug #8622]
* test/ruby/test_settracefunc.rb: add a test.



git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@43237 b2dd03c8-39d4-4d8f-98ff-823fe69b080e