build: Experimental support to build using precompiled headers

This type of build needs to be explicitly enabled using --with-pch
configure option.

Change-Id: I02dc304187d54c3cf40f1d51b1b11b21f868e225
diff --git a/src/security/certificate-cache-ttl.cpp b/src/security/certificate-cache-ttl.cpp
index f5482a3..9538d95 100644
--- a/src/security/certificate-cache-ttl.cpp
+++ b/src/security/certificate-cache-ttl.cpp
@@ -5,13 +5,12 @@
  * See COPYING for copyright and distribution information.
  */
 
+#include "common.hpp"
+
 #include "certificate-cache-ttl.hpp"
 
-#include <iostream>
-
 #include "../util/logging.hpp"
 
-
 INIT_LOGGER("CertificateCacheTtl")
 
 using namespace std;