stb_truetype: Silence warnings of winding_lengths

Coverty scan shows potential warnings of winding_lengths. Forcing it to be a NULL fixes the issue.

stb_truetype.h

@@ -3229,8 +3229,9 @@ error:
 
 STBTT_DEF void stbtt_Rasterize(stbtt__bitmap *result, float flatness_in_pixels, stbtt_vertex *vertices, int num_verts, float scale_x, float scale_y, float shift_x, float shift_y, int x_off, int y_off, int invert, void *userdata)
 {
-   float scale = scale_x > scale_y ? scale_y : scale_x;
-   int winding_count, *winding_lengths;
+   float scale            = scale_x > scale_y ? scale_y : scale_x;
+   int winding_count      = 0;
+   int *winding_lengths   = NULL;
    stbtt__point *windings = stbtt_FlattenCurves(vertices, num_verts, flatness_in_pixels / scale, &winding_lengths, &winding_count, userdata);
    if (windings) {
       stbtt__rasterize(result, windings, winding_lengths, winding_count, scale_x, scale_y, shift_x, shift_y, x_off, y_off, invert, userdata);