(usage): Remove third program_name argument -- there

were only two `%s' in the format string.

src/md5sum.c

@@ -122,7 +122,7 @@ The sums are computed as described in RFC 1321.  When checking, the input\n\
 should be a former output of this program.  The default mode is to print\n\
 a line with checksum, a character indicating type (`*' for binary, ` ' for\n\
 text), and name for each FILE.\n"),
-	      program_name, program_name, program_name);
+	      program_name, program_name);
       puts (_("\nReport bugs to <bug-textutils@gnu.org>."));
     }