fallout of cleaning-up libutils includes

Test: run & compile
Bug: n/a
Change-Id: I63585ed5a764b9ce7af2187b79ca0c83e683fd7f
diff --git a/services/audioflinger/FastThread.cpp b/services/audioflinger/FastThread.cpp
index dca7bf9..caf7905 100644
--- a/services/audioflinger/FastThread.cpp
+++ b/services/audioflinger/FastThread.cpp
@@ -22,6 +22,7 @@
 #include "Configuration.h"
 #include <linux/futex.h>
 #include <sys/syscall.h>
+#include <cutils/atomic.h>
 #include <utils/Log.h>
 #include <utils/Trace.h>
 #include "FastThread.h"