Only mix first two channels on android

jni/OpenAL/OpenAL32/Include/alu.h

@@ -1,6 +1,8 @@
 #ifndef _ALU_H_
 #define _ALU_H_
 
+#include "config.h"
+
 #include "AL/al.h"
 #include "AL/alc.h"
 #include "AL/alext.h"
@@ -71,10 +73,13 @@ typedef enum {
     BACK_CENTER,
     SIDE_LEFT,
     SIDE_RIGHT,
-
-    MAXCHANNELS
 } Channel;
 
+#ifndef MAXCHANNELS
+#define MAXCHANNELS (SIDE_RIGHT+1)
+#error MAXCHANNELS
+#endif
+
 #define BUFFERSIZE 4096
 
 #define FRACTIONBITS (14)

jni/OpenAL/include/config.h

@@ -8,6 +8,10 @@
 
 /* Define if we have the Android backend */
 #if defined(ANDROID)
+
+// Stereo only on Android back-ends
+#define MAXCHANNELS 3
+
 #if defined(POST_FROYO)
 #define HAVE_OPENSLES 1
 #endif