windows fix for previous commit

libp2p/CMakeLists.txt

@@ -14,7 +14,10 @@ aux_source_directory(. SRC_LIST)
 # we may not use it in libp2p, but one of our dependecies is including leveldb in header file
 # and windows is failing to build without that
 include_directories(${LEVELDB_INCLUDE_DIRS})
-include_directories(${MINIUPNPC_INCLUDE_DIRS})
+
+if (MINIUPNPC_FOUND)
+	include_directories(${MINIUPNPC_INCLUDE_DIRS})
+endif()
 include_directories(..)
 
 set(EXECUTABLE p2p)