build: make precompiled headers more useful

This can reduce the compilation time of a release
build (without tests) by more than 40%

Refs: #5212
Change-Id: I977aff0c0c7becbfee8a8b55605b81d0c014829b
diff --git a/daemon/face/unicast-udp-transport.hpp b/daemon/face/unicast-udp-transport.hpp
index 7c96fef..82982fc 100644
--- a/daemon/face/unicast-udp-transport.hpp
+++ b/daemon/face/unicast-udp-transport.hpp
@@ -28,6 +28,8 @@
 
 #include "datagram-transport.hpp"
 
+#include <boost/asio/ip/udp.hpp>
+
 namespace nfd::face {
 
 NFD_LOG_MEMBER_DECL_SPECIALIZED((DatagramTransport<boost::asio::ip::udp, Unicast>));