avcodec: increase AV_INPUT_BUFFER_PADDING_SIZE to 64

AVX-512 support has been introduced, and even if no functions currently
use zmm registers (able to load as much as 64 bytes of consecutive data
per instruction), they will be added eventually.
Reviewed-by: Rostislav Pehlivanov <atomnuker@gmail.com>
Tested-by: Michael Niedermayer <michael@niedermayer.cc>
Signed-off-by: James Almer <jamrial@gmail.com>

libavcodec/avcodec.h

@@ -767,7 +767,7 @@ typedef struct AVCodecDescriptor {
  * Note: If the first 23 bits of the additional bytes are not 0, then damaged
  * MPEG bitstreams could cause overread and segfault.
  */
-#define AV_INPUT_BUFFER_PADDING_SIZE 32
+#define AV_INPUT_BUFFER_PADDING_SIZE 64
 
 /**
  * @ingroup lavc_encoding

libavcodec/x86/hevc_sao.asm

@@ -198,7 +198,7 @@ HEVC_SAO_BAND_FILTER 64, 2
 ;******************************************************************************
 
 %define MAX_PB_SIZE  64
-%define PADDING_SIZE 32 ; AV_INPUT_BUFFER_PADDING_SIZE
+%define PADDING_SIZE 64 ; AV_INPUT_BUFFER_PADDING_SIZE
 %define EDGE_SRCSTRIDE 2 * MAX_PB_SIZE + PADDING_SIZE
 
 %macro HEVC_SAO_EDGE_FILTER_INIT 0

libavcodec/x86/hevc_sao_10bit.asm

@@ -190,7 +190,7 @@ HEVC_SAO_BAND_FILTER 12, 64, 4
 ;******************************************************************************
 
 %define MAX_PB_SIZE  64
-%define PADDING_SIZE 32 ; AV_INPUT_BUFFER_PADDING_SIZE
+%define PADDING_SIZE 64 ; AV_INPUT_BUFFER_PADDING_SIZE
 %define EDGE_SRCSTRIDE 2 * MAX_PB_SIZE + PADDING_SIZE
 
 %macro PMINUW 4