message: Adds linker flag to allow multiple defnitions for Clang builds.
diff: @@ -155,6 +155,7 @@ list(APPEND custom_compiler_flags_list AXOM_DISABLE_UNUSED_LOCAL_TYPEDEF)
  # Linker flag for allowing multiple definitions of a symbol
  blt_append_custom_compiler_flag(FLAGS_VAR AXOM_ALLOW_MULTIPLE_DEFINITIONS
  DEFAULT " "
  + CLANG "-Wl,--allow-multiple-definition"
  GNU "-Wl,--allow-multiple-definition"
  )
  list(APPEND custom_compiler_flags_list AXOM_ALLOW_MULTIPLE_DEFINITIONS)
  