Add a stub header file "feedback.h," needed to compile glibc and

linux.
       Backport from mainline
       2012-08-16  Walter Lee  <walt@tilera.com>

       * config.gcc (tilegx-*-linux*): Add feedback.h.
       (tilepro-*-linux*): Likewise.
       * config/tilegx/feedback.h: New file.
       * config/tilepro/feedback.h: New file.

git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/branches/gcc-4_7-branch@190453 138bc75d-0d04-0410-961f-82ee72b054a4