avcodec audio decoder: bump arbitrary decoded frame size limit

The limit can be reached with some WMA samples:
[wmav2 @ 0x7f9c50c1e960] output buffer size is too small for the current frame (192000 < 196608)

(cherry picked from commit 2ff3b97ba534977e08c119204a977c44a20b00d7)
Signed-off-by: Jean-Baptiste Kempf <jb@videolan.org>

modules/codec/avcodec/audio.c

@@ -234,8 +234,8 @@ int InitAudioDec( decoder_t *p_dec, AVCodecContext *p_context,
         p_sys->i_output_max = 0;
         break;
     }
-    if( p_sys->i_output_max < AVCODEC_MAX_AUDIO_FRAME_SIZE )
-        p_sys->i_output_max = AVCODEC_MAX_AUDIO_FRAME_SIZE;
+    if( p_sys->i_output_max < 2 * AVCODEC_MAX_AUDIO_FRAME_SIZE )
+        p_sys->i_output_max = 2 * AVCODEC_MAX_AUDIO_FRAME_SIZE;
     msg_Dbg( p_dec, "Using %d bytes output buffer", p_sys->i_output_max );
     p_sys->p_output = av_malloc( p_sys->i_output_max );