avcodec: free p_sys->p_ff_pic in some error paths

(cherry picked from commit 8a7520b350fb4eefa1a28ed43ac9dd7aca5b16c4)
Signed-off-by: Derk-Jan Hartman <hartman@videolan.org>

modules/codec/avcodec/video.c

@@ -349,6 +349,7 @@ int InitVideoDec( decoder_t *p_dec, AVCodecContext *p_context,
     p_sys->p_buffer_orig = p_sys->p_buffer = malloc( p_sys->i_buffer_orig );
     if( !p_sys->p_buffer_orig )
     {
+        av_free( p_sys->p_ff_pic );
         free( p_sys );
         return VLC_ENOMEM;
     }
@@ -399,6 +400,7 @@ int InitVideoDec( decoder_t *p_dec, AVCodecContext *p_context,
     if( ffmpeg_OpenCodec( p_dec ) < 0 )
     {
         msg_Err( p_dec, "cannot open codec (%s)", p_sys->psz_namecodec );
+        av_free( p_sys->p_ff_pic );
         free( p_sys->p_buffer_orig );
         free( p_sys );
         return VLC_EGENERIC;