Fix WEBRTC_AEC_DEBUG_DUMP (broken by int16->float conversion)

And in the process, make it dump WAV files instead of raw PCM.

R=andrew@webrtc.org, bjornv@webrtc.org

Review URL: https://webrtc-codereview.appspot.com/19089004

git-svn-id: http://webrtc.googlecode.com/svn/trunk@6959 4adac7df-926f-26a2-2b94-8c16560cd09d

webrtc/typedefs.h

@@ -109,4 +109,15 @@ typedef unsigned __int64    uint64_t;
 #endif
 #endif  // WARN_UNUSED_RESULT
 
+// Put after a variable that might not be used, to prevent compiler warnings:
+//   int result UNUSED = DoSomething();
+//   assert(result == 17);
+#ifndef UNUSED
+#ifdef __GNUC__
+#define UNUSED __attribute__((unused))
+#else
+#define UNUSED
+#endif
+#endif
+
 #endif  // WEBRTC_TYPEDEFS_H_