find nng Threads dependency

Author: rsjbailey

CMakeLists.txt

@@ -11,6 +11,9 @@ include(CTest)
 option(BUILD_TESTING "Build tests" ON)
 set(Boost_USE_STATIC_LIBS ON)
 include("enable_msvc_static_runtime")
+if(UNIX)
+    find_package(Threads REQUIRED)
+endif()
 find_package(nng REQUIRED)
 add_subdirectory(submodules)
 add_subdirectory(ear-production-suite)