Fix lint errors caught by go test

Test: m checkbuild
Change-Id: I5b8522aa9da22fc595e4f26c23e7836de59bdfa2
diff --git a/cmd/dep_fixer/main.go b/cmd/dep_fixer/main.go
index bac3772..0647fb2 100644
--- a/cmd/dep_fixer/main.go
+++ b/cmd/dep_fixer/main.go
@@ -29,7 +29,7 @@
 
 func main() {
 	flag.Usage = func() {
-		fmt.Fprintf(os.Stderr, "Usage: %s <depfile.d>")
+		fmt.Fprintf(os.Stderr, "Usage: %s <depfile.d>", os.Args[0])
 		flag.PrintDefaults()
 	}
 	output := flag.String("o", "", "Optional output file (defaults to rewriting source if necessary)")