image_test: tweak testing to open image in more modes

tests/image_test.c

@@ -91,6 +91,7 @@ int main(int argc, char **argv)
          unsigned char *data;
          printf("%s\n", argv[i]);
          res = stbi_info(argv[i], &w2, &h2, &n2);
+         data = stbi_load(argv[i], &w, &h, &n, 0); if (data) free(data); else printf("Failed &n\n");
          data = stbi_load(argv[i], &w, &h, &n, 4); if (data) free(data); else printf("Failed &n\n");
          data = stbi_load(argv[i], &w, &h,  0, 1); if (data) free(data); else printf("Failed 1\n");
          data = stbi_load(argv[i], &w, &h,  0, 2); if (data) free(data); else printf("Failed 2\n");