dxva2: Fix some warnings about incompatible pointer type

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

libavcodec/dxva2_h264.c

@@ -293,7 +293,7 @@ static int commit_bitstream_and_slice_buffer(AVCodecContext *avctx,
     /* Create an annex B bitstream buffer with only slice NAL and finalize slice */
     if (FAILED(IDirectXVideoDecoder_GetBuffer(ctx->decoder,
                                                DXVA2_BitStreamDateBufferType,
-                                               &dxva_data, &dxva_size)))
+                                               (void **)&dxva_data, &dxva_size)))
         return -1;
     current = dxva_data;
     end = dxva_data + dxva_size;

libavcodec/dxva2_mpeg2.c

@@ -160,7 +160,7 @@ static int commit_bitstream_and_slice_buffer(AVCodecContext *avctx,
 
     if (FAILED(IDirectXVideoDecoder_GetBuffer(ctx->decoder,
                                               DXVA2_BitStreamDateBufferType,
-                                              &dxva_data, &dxva_size)))
+                                              (void **)&dxva_data, &dxva_size)))
         return -1;
     current = dxva_data;
     end = dxva_data + dxva_size;

libavcodec/dxva2_vc1.c

@@ -178,7 +178,7 @@ static int commit_bitstream_and_slice_buffer(AVCodecContext *avctx,
 
     if (FAILED(IDirectXVideoDecoder_GetBuffer(ctx->decoder,
                                               DXVA2_BitStreamDateBufferType,
-                                              &dxva_data, &dxva_size)))
+                                              (void **)&dxva_data, &dxva_size)))
         return -1;
 
     result = data_size <= dxva_size ? 0 : -1;