transform: invert horizontal and vertical flip

This is consistent with the current mouse filter, and how people tend
to interpret the horizontal and vertical words. Until now, VLC would
refer to the rotational axis direction rather than the direction of the
changed dimension.

Fixes: LB#568750
(cherry picked from commit bf66354d0205141d146f7f8dd913e0448665519c)

modules/video_filter/transform.c

@@ -462,7 +462,7 @@ static void FilterPlanar( vout_thread_t *p_vout,
             }
             break;
 
-        case TRANSFORM_MODE_HFLIP:
+        case TRANSFORM_MODE_VFLIP:
             for( i_index = 0 ; i_index < p_pic->i_planes ; i_index++ )
             {
                 uint8_t *p_in = p_pic->p[i_index].p_pixels;
@@ -481,7 +481,7 @@ static void FilterPlanar( vout_thread_t *p_vout,
             }
             break;
 
-        case TRANSFORM_MODE_VFLIP:
+        case TRANSFORM_MODE_HFLIP:
             for( i_index = 0 ; i_index < p_pic->i_planes ; i_index++ )
             {
                 uint8_t *p_in = p_pic->p[i_index].p_pixels;
@@ -673,7 +673,7 @@ static void FilterYUYV( vout_thread_t *p_vout,
 
     switch( p_vout->p_sys->i_mode )
     {
-        case TRANSFORM_MODE_HFLIP:
+        case TRANSFORM_MODE_VFLIP:
             /* Fall back on the default implementation */
             FilterPlanar( p_vout, p_pic, p_outpic );
             return;
@@ -800,7 +800,7 @@ static void FilterYUYV( vout_thread_t *p_vout,
             }
             break;
 
-        case TRANSFORM_MODE_VFLIP:
+        case TRANSFORM_MODE_HFLIP:
             for( i_index = 0 ; i_index < p_pic->i_planes ; i_index++ )
             {
                 uint8_t *p_in = p_pic->p[i_index].p_pixels;