Make dg-extract-results.sh explicitly treat .{sum,log} files as text
This merges Sergio's fix from GCC:
https://gcc.gnu.org/ml/gcc-patches/2014-12/msg01293.html
gdb/testsuite/ChangeLog:
2015-03-09 Pedro Alves <palves@redhat.com>
Merge dg-extract-results.sh from GCC upstream (r218843).
2014-12-17 Sergio Durigan Junior <sergiodj@redhat.com>
* dg-extract-results.sh: Use --text with grep to avoid issues with
binary files. Fall back to cat -v, if that doesn't work.