Prevent the interactive conflict resolver from segfaulting on "df" and "m"
options for binary files by hiding these options.

This is a mere workaround and not a proper fix to underlying state model.

* subversion/svn/conflict-callbacks.c
  (handle_text_conflict): Add TODO marking the whole logic as "outdated".
                          Make sure the MY_ABSPATH string is available
                          for those options that will use it.

git-svn-id: https://svn.apache.org/repos/asf/subversion/trunk@1645578 13f79535-47bb-0310-9956-ffa450edef68