what: print filenames unconditionally

[mknos]

• Print name once per file argument, including files containing zero matches
• Empty filename '' is generally invalid and would fail earlier in open()

%perl what /bin/gcc /bin/gprof ''
/bin/gcc:
/bin/gprof:
	 Copyright (c) 1983 Regents of the University of California.
Unable to open '': No such file or directory

[briandfoy]

changes: don't need to test the filename for length