core: slim down `common.hpp`

Change-Id: I875c35147edd2261fbaa24e809c170d5cd9b94d3
diff --git a/daemon/face/lp-reliability.cpp b/daemon/face/lp-reliability.cpp
index 107212e..4f26e5d 100644
--- a/daemon/face/lp-reliability.cpp
+++ b/daemon/face/lp-reliability.cpp
@@ -30,6 +30,8 @@
 
 #include <ndn-cxx/lp/fields.hpp>
 
+#include <set>
+
 namespace nfd::face {
 
 NFD_LOG_INIT(LpReliability);