Revert "swscale: fix integer overflows in RGB pixel writing."

This reverts commit 77d88b87.

The revert fixes actual overflows and a segfault as the variables
are signed and can be negative.

Conflicts:

	libswscale/swscale.c
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

libswscale/swscale.c

@@ -990,7 +990,7 @@ YUV2PACKED16WRAPPER(yuv2, rgb48, bgr48le, PIX_FMT_BGR48LE)
  * correct RGB values into the destination buffer.
  */
 static av_always_inline void
-yuv2rgb_write(uint8_t *_dest, int i, unsigned Y1, unsigned Y2,
+yuv2rgb_write(uint8_t *_dest, int i, int Y1, int Y2,
               unsigned A1, unsigned A2,
               const void *_r, const void *_g, const void *_b, int y,
               enum PixelFormat target, int hasAlpha)