Use the information from the EXTERNALS storage to drive the
relocation of externals, instead of the svn:externals property.

* subversion/libsvn_client/relocate.c
  (relocate_externals): Remove function. Fold into caller.
  (svn_client_relocate2): Read EXTERNALS instead of getting and parsing
    svn:externals.


git-svn-id: https://svn.apache.org/repos/asf/subversion/trunk@1627338 13f79535-47bb-0310-9956-ffa450edef68