Dust off deprecation warnings from libsvn_client/export.c.
Dust off deprecation warnings from libsvn_client/export.c.

* subversion/libsvn_client/export.c
  (copy_versioned_files, add_directory, add_file): Use svn_{dirent,uri}_join().


git-svn-id: f8a4e5e023278da1e04e203c7fe051e3c4285d88@879681 13f79535-47bb-0310-9956-ffa450edef68

YueLinHo/Subversion,YueLinHo/Subversion,YueLinHo/Subversion,wbond/subversion,YueLinHo/Subversion,wbond/subversion,YueLinHo/Subversion,YueLinHo/Subversion,YueLinHo/Subversion,wbond/subversion,YueLinHo/Subversion,wbond/subversion,wbond/subversion,wbond/subversion,wbond/subversion