Fix an unused variable warning on windows.
Fix an unused variable warning on windows.

* subversion/libsvn_client/export.c
  (copy_versioned_files): Move variable declaration into tighter scope, and
    only declare it if it will be used.

jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion