Update net/vnstat to 1.11

Fix a few pkglint warnings

Upstream changes
----------------

1.11 / 1-Jun-11

- Fix: Memory allocation was miscalculated when creating interface list from
  /sys/class/net when /proc/net/dev wasn't available which in turn could
  crash the daemon
- Fix: Daemon database cache could remain empty after a -HUP signal
- Fix: Don't make temp directory in vnstat.cgi writable for everyone
- Import GNU/kFreeBSD support from Debian
  (#608963, patch by Mats Erik Andersson)
- Remove usage of GNU only '-D' option for install for BSD in Makefile
- The daemon now automatically creates databases for available interfaces
  if no databases are found during startup

1.10 / 2-Jan-10

- Fix: Buffer overflow was possible in hourly image output when RateUnit=1
  and HourlyRate=1
- Fix: Minor memory leak was possible in the handling of HUP signal in daemon
- Fix: Graphical elements weren't correctly aligned in summary image
  when header wasn't visible (-nh)
- Fix: --delete didn't work
- Possibility to merge statistics from several databases and save
  the end result to a new database (--mergesaved)
- Added validation of database cache in daemon in order to be more robust
  in case of system memory corruption
- Support for --style to -l (live mode)
- Alternative print mode to -l (live mode) with optional parameter
- Present options and elements in man pages in alphabetical order
- Code cleanup

(gls)