* vm_backtrace.c, include/ruby/debug.h: add new APIs
* VALUE rb_profile_frame_method_name(VALUE frame)
* VALUE rb_profile_frame_qualified_method_name(VALUE frame)
* iseq.c (rb_iseq_klass), internal.h: add new internal function
  rb_iseq_method_name().
* ext/-test-/debug/profile_frames.c (profile_frames),
  test/-ext-/debug/test_profile_frames.rb: add a test.



git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@43199 b2dd03c8-39d4-4d8f-98ff-823fe69b080e