Don't allow externals to be deleted with 'svn rm' under any circumstances.

File externals could be deleted with the --force or --keep-local options.

Found by: Florin <support@syncrosvnclient.com>

* subversion/libsvn_client/delete.c
  (check_external): New helper function which raises an error if the path
   about to be deleted is an external. Split out of ...
  (can_delete_node): ... this function, which isn't called in case the
   --force or --kee-local options are used.
  (svn_client__wc_delete, svn_client__wc_delete_many): Unconditionally call
   the check_external() helper function before calling can_delete_node().


git-svn-id: https://svn.apache.org/repos/asf/subversion/trunk@1464992 13f79535-47bb-0310-9956-ffa450edef68
'svnadmin info': sketch the public API.

Declare the new APIs:
* subversion/include/svn_fs.h
  (svn_fs_info, svn_fs_info_t, svn_fs_info_dup): New.

* subversion/include/svn_repos.h
  (svn_repos_info, svn_repos_info_t, svn_repos_info_dup): New.
  (svn_repos_capabilities): New.

And provide "Not implemented" definitions:

* subversion/libsvn_fs/fs-loader.c
  (svn_fs_info, svn_fs_info_dup): Dummy implementations.

* subversion/libsvn_repos/repos.c
  (svn_repos_info, svn_repos_info_dup): Dummy implementations.
  (svn_repos_capabilities): Dummy implementation.


git-svn-id: https://svn.apache.org/repos/asf/subversion/trunk@1464993 13f79535-47bb-0310-9956-ffa450edef68