Removed build flag in CMake script

CMakeLists.txt

@@ -4,7 +4,7 @@ cmake_minimum_required (VERSION 2.8)
 project (zerotiercore)
 
 set (PROJ_DIR ${PROJECT_SOURCE_DIR})
-set (ZT_DEFS -std=c++11 "-DZT_SDK=1")
+set (ZT_DEFS -std=c++11)
 
 file(GLOB core_src_glob ${PROJ_DIR}/node/*.cpp)
 add_library(zerotiercore STATIC ${core_src_glob})