libopencore-amr: check return value of avcodec_alloc_frame()

Signed-off-by: Paul B Mahol <onemda@gmail.com>
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

libavcodec/libopencore-amr.c

@@ -196,6 +196,8 @@ static av_cold int amr_nb_encode_init(AVCodecContext *avctx)
 
     avctx->frame_size  = 160;
     avctx->coded_frame = avcodec_alloc_frame();
+    if (!avctx->coded_frame)
+        return AVERROR(ENOMEM);
 
     s->enc_state = Encoder_Interface_init(s->enc_dtx);
     if (!s->enc_state) {