Add a test for the new spillbuf reader.
Add a test for the new spillbuf reader.

* subversion/tests/libsvn_subr/spillbuf-test.c:
  (test_spillbuf_reader): new test
  (test_funcs): add the new test


git-svn-id: f8a4e5e023278da1e04e203c7fe051e3c4285d88@1173667 13f79535-47bb-0310-9956-ffa450edef68

YueLinHo/Subversion,YueLinHo/Subversion,YueLinHo/Subversion,YueLinHo/Subversion,YueLinHo/Subversion,YueLinHo/Subversion,YueLinHo/Subversion,YueLinHo/Subversion