fileadder: print the generated files only when there is no image to write

The image rule no longer passes -p, so fileadder fell through to printing
html_data.h and html_data.c on stdout on every image build. The listing is
only useful when fileadder is run without an image, to see what it would
generate.

tools/fileadder.c

@@ -441,7 +441,7 @@ int main(int argc, char **argv)
 		fputs(xbuf, ofile);
 		fputs(fbuf, ofile);
 		fclose(ofile);
-	} else if (addsDir){
+	} else if (addsDir && !argv[arg_index]) {
 		puts(dbuf);
 		puts(xbuf);
 		puts(ibuf);