The order of making binding should be stack (frame) top to bottom.
[Bug #7635]
And also fix issue of collecting klass. Collecting klass is same
as TracePoint#defined_class.
(previous version, it returns T_ICLASS (internal objects).
* test/-ext-/debug/test_debug.rb: add a test.
* ext/-test-/debug/extconf.rb, init.c, inspector.c: ditto.
* vm_backtrace.c: remove magic number and add enum CALLER_BINDING_*.
* vm_backtrace.c, include/ruby/debug.h: add new C api (experimental)
rb_debug_inspector_frame_self_get().
* vm.c, vm_core.h, vm_trace.c: move decl. of
rb_vm_control_frame_id_and_class() and constify first parameter.
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@38970 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
