ra_serf: Support older expat versions - such as 1.95.2 bundled with apr-util.
ra_serf: Support older expat versions - such as 1.95.2 bundled with apr-util.

* subversion/libsvn_ra_serf/util.c
  (XML_STATUS_OK/XML_STATUS_ERROR): #define if not present as this is only in
  newer expat 1.95.x/2.0+ versions.
  (start_xml, end_xml, cdata_xml): Remove XMLCALL decoration that appears to
  not be strictly required on Win32.

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