aac: Only set sample rate and object type from ADTS if output hasn't been configured.

Long term it would be nice to support error resilient reconfiguration
but right now setting this every frame does more harm than help.
Signed-off-by: Luca Barbato <lu_zero@gentoo.org>

libavcodec/aacdec.c

@@ -2092,10 +2092,10 @@ static int parse_adts_frame_header(AACContext *ac, GetBitContext *gb)
         if (ac->output_configured != OC_LOCKED) {
             ac->m4ac.sbr = -1;
             ac->m4ac.ps  = -1;
+            ac->m4ac.sample_rate     = hdr_info.sample_rate;
+            ac->m4ac.sampling_index  = hdr_info.sampling_index;
+            ac->m4ac.object_type     = hdr_info.object_type;
         }
-        ac->m4ac.sample_rate     = hdr_info.sample_rate;
-        ac->m4ac.sampling_index  = hdr_info.sampling_index;
-        ac->m4ac.object_type     = hdr_info.object_type;
         if (!ac->avctx->sample_rate)
             ac->avctx->sample_rate = hdr_info.sample_rate;
         if (hdr_info.num_aac_frames == 1) {