gpujpegtool: use gpujpeg_image_parameters initializer

Instead of zero-initialization, initialize with
gpujpeg_default_image_parameters().

This allows running with "incorrect" extension like '.bla', eg.:
```
gpujpegtool -e 1920x1080.tst out.jpg    # prepare input
gpujpegtool -d out.jpg out.bla
```

Not sure if this is actually better behavior but it was written so
intentional by the commit 3313aa0. It ceased to work with further
updates. (Now produces additional warning inside the library: `[GPUJPEG]
[Error] GPUJPEG_IMAGE_FILE_UNKNOWN should not be passed!`).

Author: MartinPulec

src/main.c

@@ -179,7 +179,7 @@ adjust_params(struct gpujpeg_parameters* param, struct gpujpeg_image_parameters*
               const char* out, bool encode, const struct options* opts)
 {
     // if possible, read properties from file
-    struct gpujpeg_image_parameters file_param_image = { 0, 0, GPUJPEG_NONE, GPUJPEG_PIXFMT_NONE, 0 };
+    struct gpujpeg_image_parameters file_param_image = gpujpeg_default_image_parameters();
     const char *raw_file = encode ? in : out;
     gpujpeg_image_get_properties(raw_file, &file_param_image, encode);
     param_image->width = USE_IF_NOT_NULL_ELSE(param_image->width, file_param_image.width);