fix compilation errors on Windows

Author: trongnhanuit

CMakeLists.txt

@@ -183,7 +183,11 @@ if (NOT CMAPLE_FLAGS MATCHES "single")
         set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -fopenmp")
     elseif (CMAKE_CXX_COMPILER_ID MATCHES "Clang")
         if (APPLE OR WIN32)
-            set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Xpreprocessor -fopenmp")
+            if (WIN32)
+                set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Xpreprocessor -openmp -pthread")
+            else()
+                set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Xpreprocessor -fopenmp -pthread")
+            endif()
             set(CMAKE_EXE_LINKER_FLAGS "${CMAKE_EXE_LINKER_FLAGS} -lomp")
         else()
             set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -fopenmp")