put back 32bit alignment with a comment as to why

src/zm_ffmpeg_camera.cpp

@@ -1087,9 +1087,10 @@ int FfmpegCamera::transfer_to_image(
     return -1;
   }
 #if LIBAVUTIL_VERSION_CHECK(54, 6, 0, 6, 0)
+  // From what I've read, we should align the linesizes to 32bit so that ffmpeg can use SIMD instructions too.
   int size = av_image_fill_arrays(
       output_frame->data, output_frame->linesize,
-      directbuffer, imagePixFormat, width, height, 1);
+      directbuffer, imagePixFormat, width, height, 32);
   if ( size < 0 ) {
     Error("Problem setting up data pointers into image %s",
         av_make_error_string(size).c_str());