Following up on r1483993, update some callers of svn_io_file_flush_to_disk that
where an fflush is enough for correct behavior. The conflict edit code in svn
doesn't store the paths, so doesn't need power failure guarantees.

* subversion/svn/conflict-callbacks.c
  (edit_prop_conflict): Use a normal file flush.

* subversion/svn/file-merge.c
  (edit_chunk): Use a normal file flush.

* subversion/tests/libsvn_client/client-test.c
  (edit_chunk): Use a normal file flush.


git-svn-id: https://svn.apache.org/repos/asf/subversion/trunk@1483995 13f79535-47bb-0310-9956-ffa450edef68