Speed up objdump when displaying disassembly mixed with line number and source code...

Speed up objdump when displaying disassembly mixed with line number and source code information.

bfd	* dwarf2.c (lookup_address_in_function_table): Return early if
	there are no functions in the given comp unit, or if the high
	address of the last function in the comp unit is less than the
	desired address.

binutils * objdump.c (display_file): Add new parameter 'last_file'.  If
	last_file is true, do not call bfd_close at the end of the
	function.
	(main): Set the value of the last_file parameter when calling
	display_file.