avfilter/af_aphaser: Change type to int as its accessed as int via AVOptions

This fixes depending on implementation defined behavior
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

libavfilter/af_aphaser.c

@@ -37,7 +37,7 @@ typedef struct AudioPhaserContext {
     double decay;
     double speed;
 
-    enum WaveType type;
+    int type;
 
     int delay_buffer_length;
     double *delay_buffer;