add linux -fopenmp flag

deploy/cpp_infer/CMakeLists.txt

@@ -67,9 +67,12 @@ if (WIN32)
 	message("cmake cxx debug flags " ${CMAKE_CXX_FLAGS_DEBUG})
 	message("cmake cxx release flags " ${CMAKE_CXX_FLAGS_RELEASE})
 else()
-    set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -g -o3 -std=c++11")
+	if(WITH_MKL)
+		set(FLAG_OPENMP "-fopenmp")
+    endif()
+    set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -g -o3 ${FLAG_OPENMP} -std=c++11")
     set(CMAKE_STATIC_LIBRARY_PREFIX "")
-	message("flags" ${CMAKE_CXX_FLAGS})
+	message("cmake cxx flags" ${CMAKE_CXX_FLAGS})
 endif()
 
 if (WITH_GPU)