Fix issue 3404: svnsync fails when source has ^M in svn:* properties (eol style)

svnsync subcommands sync and copy-revprops have been taught how to do
eol-style normalization of revision and node properties which
svn_prop_needs_translation.

Normalization will always be performed for a target repository
initialized with --fix-svn-prop-eol-style. Alternatively this option
is also understood by the sync and copy-revprops subcommands to mean
perform eol-normalization just for the current execution.

* subversion/include/svn_props.h
  (SVNSYNC_PROP_FIX_SVN_PROP_EOL_STYLE):

* subversion/libsvn_subr/properties.c
  (svn_prop_is_boolean):

* subversion/svnsync/main.c
  (svn_subst.h, svn_string.h): #include
  (svnsync_opt_fix_svn_prop_eol_style): new enum value. Represents the option
   --fix-svn-prop-eol-style on subcommands init, sync and copy-revprops.
  (svnsync_cmd_table): svnsync_opt_fix_svn_prop_eol_style added to entries for
   init, sync and copy-revprops.
  (svnsync_options): added svnsync_opt_fix_svn_prop_eol_style.
  (opt_baton_t): new fix_svn_prop_eol_style, records presence of option.
  (subcommand_baton_t): new fix_svn_prop_eol_style, meaning subcommand should
   perform eol-style normalization on svn:* properties as appropriate.
  (normalize_svn_string_eol_style): new, eol normalization for 1 svn_string_t.
  (normalize_revprop_eol_style): new, eol normalization for a revprop hash.
  (copy_revprops): new argument fix_svn_prop_eol_style which causes eol-style
   normalization to be done during revprop copying.
  (make_subcommand_baton): copy fix_svn_prop_eol_style form opt_baton.
  (do_initialize): record presence of --fix-svn-prop-eol-style as property
   svn:sync-fix-svn-prop-eol-style of revision zero of target. Also
   optionally perform eol-style normalization on revprops copied from source
   repository.
  (edit_baton_t): new fix_svn_prop_eol_style, which determines if the edit
   drive should do eol-style normalization on svn:* properties.
  (change_file_prop, change_dir_prop): may perform eol-style normalization.
  (get_sync_editor): new argument fix_svn_prop_eol_style, which serves to
   get this flag from the subcommand_baton into the edit_baton with some help
   form replay_rev_started.
  (replay_rev_started): may perform normalization of copied revprops.
   Provides fix_svn_prop_eol_style for sync_baton (an edit_baton_t).
  (replay_rev_finished): may perform normalization of copied revprops.
  (do_synchronize): may perform normalization of copied revrops while
   cleaning up form a previous call that didn't run to completion.
  (synchronize_cmd, copy_revprops_cmd): sets fix_svn_prop_eol_style on the
   subcommand_baton when init has left the corresponding property behind in
   revision zero.
  (do_copy_revprops): may perform normalization of copied revprops.
  (info_cmd): one line of ourput generated iff svn:sync-fix-svn-prop-eol-style
   is present in revision zero.
  (main): handle svnsync_opt_fix_svn_prop_eol_style, set flag in opt_baton.