libavfilter/af_amerge: Do not depend on SWR_CH_MAX

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

libavfilter/af_amerge.c

@@ -27,12 +27,13 @@
 #include "libavutil/bprint.h"
 #include "libavutil/channel_layout.h"
 #include "libavutil/opt.h"
-#include "libswresample/swresample.h" // only for SWR_CH_MAX
 #include "avfilter.h"
 #include "audio.h"
 #include "bufferqueue.h"
 #include "internal.h"
 
+#define SWR_CH_MAX 32
+
 typedef struct {
     const AVClass *class;
     int nb_inputs;