Fix a const warning.
Fix a const warning.

Note: APR or our function may need to change signatures to clean this up
  "properly" so we don't have to cast it.

* subversion/libsvn_wc/props.c:
  (svn_wc_parse_externals_descriptions): cast a const into the array to
    avoid a compiler warning.

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