remove the last remaining -debugdir buffer

We were still printing files into a buffer, which got left behind from
when we used to store the obfuscated source in object files.

All that code is gone, so this buffer is now just wasting CPU cycles and
memory.

main.go

@@ -688,15 +688,12 @@ func transformCompile(args []string) ([]string, error) {
 		}
 		defer tempFile.Close()
 
-		obfSrc := &bytes.Buffer{}
-		printWriter := io.MultiWriter(tempFile, obfSrc)
-
 		for _, comment := range detachedComments[i] {
-			if _, err := printWriter.Write([]byte(comment + "\n")); err != nil {
+			if _, err := tempFile.Write([]byte(comment + "\n")); err != nil {
 				return nil, err
 			}
 		}
-		if err := printConfig.Fprint(printWriter, fset, file); err != nil {
+		if err := printConfig.Fprint(tempFile, fset, file); err != nil {
 			return nil, err
 		}
 		if opts.DebugDir != "" {