Copy from vc Vcmacro.cmake file (remove my changes for suppressing unused function warning)

math/vc/cmake/VcMacros.cmake

@@ -370,9 +370,6 @@ macro(vc_set_preferred_compiler_flags)
       vc_add_compiler_flag(Vc_DEFINITIONS "-Wno-local-type-template-args")
       vc_add_compiler_flag(Vc_DEFINITIONS "-Wno-unnamed-type-template-args")
 
-      #LM: disable this warning appearing from version 3.4 (5.1) 
-      vc_add_compiler_flag(Vc_DEFINITIONS "-Wno-unused-function")
-
       if(NOT DEFINED Vc_INSIDE_ROOT)  # ROOT has to set this up
          AddCompilerFlag(-stdlib=libc++)
       endif()