Move deprecated utf function to deprecated.c

* subversion/libsvn_subr/deprecated.c
  (svn_utf_cstring_from_utf8_ex): Move function here..

* subversion/libsvn_subr/utf.c
  (svn_utf_cstring_from_utf8_ex): ... that used to be here.


git-svn-id: https://svn.apache.org/repos/asf/subversion/trunk@1531006 13f79535-47bb-0310-9956-ffa450edef68