Fix debug builds on Apple Clang 9.0.0 (macOS High Sierra)

lib/cli/calistcommand.cpp

@@ -24,6 +24,7 @@
 #include "base/application.hpp"
 #include "base/tlsutility.hpp"
 #include "base/json.hpp"
+#include <iostream>
 
 using namespace icinga;
 namespace po = boost::program_options;

lib/cli/pkisavecertcommand.cpp

@@ -22,6 +22,7 @@
 #include "base/logger.hpp"
 #include "base/tlsutility.hpp"
 #include "base/console.hpp"
+#include <iostream>
 
 using namespace icinga;
 namespace po = boost::program_options;

lib/remote/jsonrpc.cpp

@@ -23,6 +23,7 @@
 #include "base/console.hpp"
 #include "base/scriptglobal.hpp"
 #include "base/convert.hpp"
+#include <iostream>
 
 using namespace icinga;