buildgcc: Show excessive arguments and bail out

Also remove a dead line that checks for unknown options: We already let
`getopt` check that.

Change-Id: I0e829b266e192757d6e455ee4cc608315bb4b7be
Signed-off-by: Nico Huber <nico.huber@secunet.com>
Reviewed-on: https://review.coreboot.org/16681
Reviewed-by: Paul Menzel <paulepanter@users.sourceforge.net>
Tested-by: build bot (Jenkins)
Reviewed-by: Patrick Georgi <pgeorgi@google.com>

util/crossgcc/buildgcc

@@ -725,11 +725,16 @@ while true ; do
 		-n|--nocolor)	shift; \
 			unset red RED green GREEN blue BLUE cyan CYAN NC;;
 		--)		shift; break;;
-		-*)		printf "Invalid option\n\n"; myhelp; exit 1;;
 		*)		break;;
 	esac
 done
 
+if [ $# -gt 0 ]; then
+	printf "Excessive arguments: $*\n"
+	myhelp
+	exit 1
+fi
+
 if [ -n "$PRINTSTABLE" ]; then
 	print_stable
 	exit 0