middle-end: On emergency dumps finish the graph generation.

When doing an emergency dump the cfg output dumps are corrupted because the
ending "}" is missing.

Normally when the pass manager finishes it would call finish_graph_dump_file to
produce this.  This is called here because each pass can dump multiple digraphs.

However during an emergency dump we only dump the current function and so after
that is done we never go back to the pass manager.

As such, we need to manually call finish_graph_dump_file in order to properly
finish off graph generation.

With this -ftree-dump-*-graph works properly during a crash dump.

gcc/ChangeLog:

	* passes.cc (emergency_dump_function): Finish graph generation.