Allow the --output option of the "ar" prorgam to extract files to locations outside...

Allow the --output option of the "ar" prorgam to extract files to locations outside of the current directory.

	* ar.c (open_output_file): Check for filename validity before
	prefixing with output directory.
	Display the constructed output filename if in verbose mode.
	(extract_file): Let open_output_file display the filename.