replay_configure() pushes and pops a Location with automatic storage
duration.  Except it fails to pop when -icount parameter "rr" isn't
given.  cur_loc then points to unused stack space, and will most
likely get clobbered in short order.

Clobbered cur_loc can make loc_pop() and error_print_loc() crash or
report bogus locations.

Broken in commit 890ad550.

I didn't take the time to find a reproducer.

Cc: Eduardo Habkost <ehabkost@redhat.com>
Signed-off-by: NMarkus Armbruster <armbru@redhat.com>
Message-Id: <1461767349-15329-3-git-send-email-armbru@redhat.com>
Reviewed-by: NEric Blake <eblake@redhat.com>
Reviewed-by: NEduardo Habkost <ehabkost@redhat.com>