Fix build using system clang.

Remove pipestats as it is unused.

Change-Id: I6e3e3c47b6f4562611f5f87b5b9ebd561f9ec033
diff --git a/src/profiling/memory/client.h b/src/profiling/memory/client.h
index a32a2a3..75de189 100644
--- a/src/profiling/memory/client.h
+++ b/src/profiling/memory/client.h
@@ -20,6 +20,7 @@
 #include <pthread.h>
 #include <stddef.h>
 
+#include <condition_variable>
 #include <mutex>
 #include <vector>