BUG/MINOR: cfgparse: Fail if the strdup() for `rule->be.name` for `use_backend` fails

This patch fixes GitHub issue #1024.

I could track the `strdup` back to commit
3a1f5fda109fc56ae127d03eaf34ce027c9542e1 which is 1.9-dev8. It's probably not
worth the effort to backport it across this refactoring.

This patch should be backported to 1.9+.
1 file changed