Allow ra_serf to compile against older 1.x APRs at the cost of performance.
Allow ra_serf to compile against older 1.x APRs at the cost of performance.

* subversion/libsvn_ra_serf/commit.c
  (private/svn_compat.h): Include
  (create_put_body): Protect call to apr_file_buffer_set with APR version check
  and leave a note here as to the implications of not having this.

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