Merge commit '0f50c53c' into release/2.4

* commit '0f50c53c':
  png: Set the color range as full range

Conflicts:
	libavcodec/pngdec.c
Merged-by: Michael Niedermayer <michaelni@gmx.at>

libavcodec/pngdec.c

@@ -918,6 +918,7 @@ static av_cold int png_dec_init(AVCodecContext *avctx)
 {
     PNGDecContext *s = avctx->priv_data;
 
+    avctx->color_range = AVCOL_RANGE_JPEG;
     s->avctx = avctx;
     s->last_picture.f = av_frame_alloc();
     s->picture.f = av_frame_alloc();

tests/ref/fate/png-ya16

 #tb 0: 1/25
-0,          0,          0,        1,    49152, 0x93ce1cd5
+0,          0,          0,        1,    49152, 0x0801ce78

tests/ref/fate/png-ya8

 #tb 0: 1/25
-0,          0,          0,        1,    49152, 0xed73bf03
+0,          0,          0,        1,    49152, 0x5a1481f8