Fix "error: 'memset' was not declared in this scope".

Change-Id: I3a1c3e9d6bdfe7e99e82d29d815fe8e73bc9bd65
diff --git a/audio_utils/spdif/FrameScanner.cpp b/audio_utils/spdif/FrameScanner.cpp
index f12e538..144a632 100644
--- a/audio_utils/spdif/FrameScanner.cpp
+++ b/audio_utils/spdif/FrameScanner.cpp
@@ -17,6 +17,8 @@
 
 #define LOG_TAG "AudioHardwareTungsten"
 
+#include <string.h>
+
 #include <utils/Log.h>
 #include <audio_utils/spdif/FrameScanner.h>