Call dummy_frame_dtor_ftype also from remove_dummy_frame
There was now a leak-like bug that if dummy_frame "disappeared" by
remove_dummy_frame then its destructor was not called. For example in the case
of 'compile code' dummy frames the injected objfile would never get freed after
some inferior longjmp out of the injected code.
gdb/ChangeLog
2015-05-13 Jan Kratochvil <jan.kratochvil@redhat.com>