mmaldec: Fix avpriv_atomic_get usage

There is no avpriv_atomic_get, instead avpriv_atomic_int_get is to be used for
integers. This fixes building mmaldec.

Signed-off-by: Julian Scheel <julian@jusst.de>
Reviewed-by: wm4 <nfxjfg@googlemail.com>
Signed-off-by: Anton Khirnov <anton@khirnov.net>

libavcodec/mmaldec.c

@@ -166,7 +166,7 @@ static void ffmmal_stop_decoder(AVCodecContext *avctx)
     }
     ctx->waiting_buffers_tail = NULL;
 
-    av_assert0(avpriv_atomic_get(&ctx->packets_buffered) == 0);
+    av_assert0(avpriv_atomic_int_get(&ctx->packets_buffered) == 0);
 
     ctx->frames_output = ctx->eos_received = ctx->eos_sent = ctx->packets_sent = ctx->extradata_sent = 0;
 }