explicitly include libc++ with clang

CMakeLists.txt

@@ -278,10 +278,15 @@ else()
   endif()
   set(USE_LTO ${USE_LTO_DEFAULT} CACHE BOOL "Use Link-Time Optimization (Release mode only)")
 
-  # There is a clang bug that does not allow to compile code that uses AES-NI intrinsics if -flto is enabled, so explicitly disable
   if(CMAKE_CXX_COMPILER_ID STREQUAL "Clang")
+    # There is a clang bug that does not allow to compile code that uses AES-NI intrinsics if -flto is enabled, so explicitly disable
     set(USE_LTO false)
+    # explicitly define stdlib for older versions of clang
+    set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -stdlib=libc++")
+    set(CMAKE_EXE_LINKER_FLAGS "${CMAKE_EXE_LINKER_FLAGS} -stdlib=libc++")
   endif()
+
+
   if(USE_LTO)
     set(RELEASE_FLAGS "${RELEASE_FLAGS} -flto")
     if(STATIC)