mandelbrot: fix inner=period coloring routine

Fixes CID717571
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

libavfilter/vsrc_mandelbrot.c

@@ -346,7 +346,7 @@ static void draw_mandelbrot(AVFilterContext *ctx, uint32_t *color, int linesize,
                         break;
                 if(j){
                     c= i-j;
-                    c= ((c<<5)&0xE0) + ((c<<16)&0xE000) + ((c<<27)&0xE00000);
+                    c= ((c<<5)&0xE0) + ((c<<10)&0xE000) + ((c<<15)&0xE00000);
                 }
                 }else if(mb->inner==CONVTIME){
                     c= floor(i*255.0/mb->maxiter+dv)*0x010101;