Added missing include for Clang.
Added missing include for Clang.

ksubramz/CppMicroServices,saschazelzer/CppMicroServices,ksubramz/CppMicroServices,saschazelzer/CppMicroServices,CppMicroServices/CppMicroServices,CppMicroServices/CppMicroServices,CppMicroServices/CppMicroServices,ksubramz/CppMicroServices,Heather/CppMicroServices,CppMicroServices/CppMicroServices,ksubramz/CppMicroServices,quinnlin/CppMicroServices,quinnlin/CppMicroServices,ksubramz/CppMicroServices,Heather/CppMicroServices,mobileFX/CppMicroServices,mobileFX/CppMicroServices,CppMicroServices/CppMicroServices