avutil/imgutils: compute the line size of bitstream formats without overflow

Fixes: signed integer overflow
Fixes: P0BVJKDC5JLx
Found during the review of https://code.ffmpeg.org/FFmpeg/FFmpeg/pulls/24756
Signed integer overflow Replicated through UnModified FFmpeg with UBSAN

libavutil/imgutils.c

@@ -69,7 +69,7 @@ int image_get_linesize(int width, int plane,
     linesize = max_step * shifted_w;
 
     if (desc->flags & AV_PIX_FMT_FLAG_BITSTREAM)
-        linesize = (linesize + 7) >> 3;
+        linesize = (linesize >> 3) + !!(linesize & 7);
     return linesize;
 }