video_filter: ball: use C99 loop declarations

modules/video_filter/ball.c

@@ -484,10 +484,9 @@ static void GaussianConvolution( picture_t *p_inpic, uint32_t *p_smooth )
     const int i_src_visible = p_inpic->p[Y_PLANE].i_visible_pitch;
     const int i_numLines = p_inpic->p[Y_PLANE].i_visible_lines;
 
-    int x,y;
-    for( y = 2; y < i_numLines - 2; y++ )
+    for( int y = 2; y < i_numLines - 2; y++ )
     {
-        for( x = 2; x < i_src_visible - 2; x++ )
+        for( int x = 2; x < i_src_visible - 2; x++ )
         {
             p_smooth[y*i_src_visible+x] = (uint32_t)(
                     /* 2 rows up */
@@ -609,9 +608,9 @@ static void FilterBall( filter_t *p_filter, picture_t *p_inpic,
        | -2 0 2 | and |  0  0  0 |
        | -1 0 1 |     | -1 -2 -1 | */
 
-    for( y = 1; y < i_numLines - 1; y++ )
+    for( int y = 1; y < i_numLines - 1; y++ )
     {
-        for( x = 1; x < i_numCols - 1; x++ )
+        for( int x = 1; x < i_numCols - 1; x++ )
         {
 
             p_grad_x[ y * i_numCols + x ] =
@@ -634,9 +633,9 @@ static void FilterBall( filter_t *p_filter, picture_t *p_inpic,
     if( p_sys->b_edgeVisible )
     {
         /* Display the edges. */
-        for( y = 1; y < i_numLines - 1; y++ )
+        for( int y = 1; y < i_numLines - 1; y++ )
         {
-            for( x = 1; x < i_numCols - 1; x++ )
+            for( int x = 1; x < i_numCols - 1; x++ )
             {
                 if( abs( p_grad_x[ y * i_numCols + x ] )
                     + abs( p_grad_y[ y * i_numCols + x ] )