Detect invalid svndiff data earlier.
Detect invalid svndiff data earlier.

* subversion/libsvn_delta/svndiff.c
  (write_handler): Check that unprocessed data is not larger that
   theoretical maximum window header size.


git-svn-id: f8a4e5e023278da1e04e203c7fe051e3c4285d88@1684077 13f79535-47bb-0310-9956-ffa450edef68

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