Continue working on CMake build system

Link to correct libs

ports/unix/CMakeLists.txt

@@ -11,4 +11,15 @@ set(lwipcontribportunix_SRCS
     port/netif/fifo.c
 )
 
+if (CMAKE_SYSTEM_NAME STREQUAL Linux)
+    link_libraries(util)
+    link_libraries(pthread)
+    link_libraries(rt)
+endif()
+
+if (CMAKE_SYSTEM_NAME STREQUAL Darwin)
+    # Darwin doesn't have pthreads or POSIX real-time extensions libs
+    link_libraries(util)
+endif()
+
 add_library(lwipcontribportunix EXCLUDE_FROM_ALL ${lwipcontribportunix_SRCS})

ports/unix/unixsim/CMakeLists.txt

@@ -2,6 +2,8 @@ cmake_minimum_required(VERSION 3.8)
 
 include(../../CMakeCommon.cmake)
 
+add_definitions(-DLWIP_DEBUG)
+
 include_directories(lwip PUBLIC
     "${CMAKE_CURRENT_SOURCE_DIR}/../../../../lwip/src/include"
     "${CMAKE_CURRENT_SOURCE_DIR}/../../../"
@@ -13,13 +15,15 @@ add_subdirectory(../../../ contrib)
 add_subdirectory(../../../../lwip/src lwip)
 add_subdirectory(../ unixport)
 
-link_libraries(pthread)
+# lwipcontribaddons is specified multiple times in target_link_libraries because of cyclic dependency
+# lwipcontribaddons call various functions in lwipcore
+# lwipcore needs tcp_hook_isn from lwipcontribaddons
 
 add_executable(simhost simhost.c)
-target_link_libraries(simhost lwipcontribportunix lwipcontribexamples lwipcontribapps lwipcontribaddons lwip)
+target_link_libraries(simhost lwipcontribexamples lwipcontribapps lwipcontribaddons lwipapps lwipcontribportunix lwipcore lwipcontribaddons)
 
 add_executable(simnode simnode.c)
-target_link_libraries(simnode lwipcontribportunix lwipcontribexamples lwipcontribapps lwipcontribaddons lwip)
+target_link_libraries(simnode lwipcontribexamples lwipcontribapps lwipcontribaddons lwipapps lwipcontribportunix lwipcore lwipcontribaddons)
 
 add_executable(simrouter simrouter.c)
-target_link_libraries(simrouter lwipcontribportunix lwipcontribexamples lwipcontribapps lwipcontribaddons lwip)
+target_link_libraries(simrouter lwipcontribexamples lwipcontribapps lwipcontribaddons lwipapps lwipcontribportunix lwipcore lwipcontribaddons)