Another attempt at resolving CID 1305629. The test of cmd == -1

may make Coverity think that other negative values of cmd (used
as an index) are possible.  Testing < 0 is a more common idiom
in any case.

Reported by:	Coverity
CID:		1305629

usr.sbin/binmiscctl/binmiscctl.c

@@ -416,7 +416,7 @@ main(int argc, char **argv)
 
 	argc--, argv++;
 	cmd = demux_cmd(argc, argv);
-	if (cmd == -1)
+	if (cmd < 0)
 		usage("Error: Unknown command \"%s\"", argv[0]);
 	argc--, argv++;