Mark the following static variables as used instead of unused:
o force_to_data
o CTOR_LIST
o do_global_dtors_aux_fini_array_entry
o frame_dummy_init_array_entry

This is necessary because Clang is smart enough to optimize out these
variables was they were marked as unused (and they are also static).
The end result was programs segfaulting because these symbols weren't
present.

This follows the upstream revision 159228 and the author of that
revision (Jan Hubicka <jh at suse.de>) allowed us to backport this to our
GPLv2 GCC.

Discussed with: core