Revision 1501049

[ Reverted in r1515085. ]

ra_serf: Do not return a serf apr_status_t.

For me, this manifested as the following error chain (with the patch already
applied; before the patch, 120171 was the only code in the chain):

    % $svn info https://svn-us.apache.org/repos/asf
    subversion/svn/info-cmd.c:663,
    subversion/libsvn_client/info.c:300,
    subversion/libsvn_client/ra.c:516,
    subversion/libsvn_client/ra.c:393,
    subversion/libsvn_ra/ra_loader.c:482: (apr_err=SVN_ERR_RA_SERF_WRAPPED_ERROR)
    svn: E230003: Unable to connect to a repository at URL 'https://svn-us.apache.org/repos/asf'
    subversion/libsvn_ra_serf/serf.c:506,
    subversion/libsvn_ra_serf/options.c:508,
    subversion/libsvn_ra_serf/util.c:817,
    subversion/libsvn_ra_serf/util.c:784: (apr_err=SVN_ERR_RA_SERF_WRAPPED_ERROR)
    svn: E230003: Error running context: An error occurred during SSL communication
    subversion/libsvn_ra_serf/util.c:784: (apr_err=120171)
    svn: E120171: APR does not understand this error code

In that, 120171 is SERF_ERROR_SSL_COMM_FAILED, which is not a useful value for
svn_error_t->apr_err (API users can't do anything with it).


* subversion/include/svn_error_codes.h
  (SVN_ERR_RA_SERF_WRAPPED_ERROR): Warn about non-standard semantics to be
    expected in presence of this error code.

* subversion/libsvn_ra_serf/util_error.c
  (svn_ra_serf__wrap_err): Wrap the serf error code by a Subversion one.