Fix path filter for the 'If' header processing in libsvn_ra_serf.

* subversion/libsvn_ra_serf/commit.c
  (setup_if_header_recursive): Following up on r1553552, fix bad example of
    argument<->variable shadowing introduced by a refactoring before
    committing.


git-svn-id: https://svn.apache.org/repos/asf/subversion/trunk@1553556 13f79535-47bb-0310-9956-ffa450edef68