vcs-svn

vcs-svn updates to clean-up compilation, lift 32-bit limitations, etc.

* jn/vcs-svn:
  vcs-svn: allow 64-bit Prop-Content-Length
  vcs-svn: suppress a signed/unsigned comparison warning
  vcs-svn: suppress a signed/unsigned comparison warning
  vcs-svn: suppress signed/unsigned comparison warnings
  vcs-svn: use strstr instead of memmem
  vcs-svn: use constcmp instead of prefixcmp
  vcs-svn: simplify cleanup in apply_one_window
  vcs-svn: avoid self-assignment in dummy initialization of pre_off
  vcs-svn: drop no-op reset methods
  vcs-svn: suppress -Wtype-limits warning
  vcs-svn: allow import of > 4GiB files
  vcs-svn: rename check_overflow and its arguments for clarity