[patch] Produce .weak_def_can_be_hidden for some linkonce_odr values

[Rafael Espíndola]

Ping.

I just tested this with the linker in Xcode 5 and the results are:

$ nm  build-with-master/bin/clang-3.4  | grep  ' T ' | wc

   21053   63159 1790901

$ nm  build-with-patch/bin/clang-3.4  | grep  ' T ' | wc

   19049   57147 1547425

Cheers,
Rafael