Add again suppression of warning for unused function in Vc for latest clang version

math/vc/cmake/VcMacros.cmake

@@ -378,7 +378,11 @@ macro(vc_set_preferred_compiler_flags)
 
       if(NOT DEFINED Vc_INSIDE_ROOT)  # ROOT has to set this up
          AddCompilerFlag(-stdlib=libc++)
+      else()
+         # disable this warning appearing from version 3.4 (5.1) 
+      	 vc_add_compiler_flag(Vc_DEFINITIONS "-Wno-unused-function")
       endif()
+
    endif()
 
    if(NOT Vc_COMPILER_IS_MSVC)