Update collectd to version 5.9.0

* remove backported upstream patches (sensors, modbus)
* remove lua patch that has been been implemented upstream
  (See collectd PR 3144)
* refresh patches and accommodate into upstream path changes
* place the 'stations' datatype for iwinfo in alpbetically
  correct place in types.db
* add libmnl dependency to 'processes' plugin required for the
  new Linux process Delay Accounting capability.
  (Alternatively the capability & requirement might be patched away
   in Makefile.am, HAVE_LIBTASKSTATS from collectd_4ea7a572)

* new plugins (disabled): ampq1, gpu_nvidia, pcie_errors,
                          write_stackdriver, write_syslog

compile-tested: ar71xx/WNDR3700 (all plugins)
run-tested: ar71xx/WNDR3700 (selected plugins)

Signed-off-by: Hannu Nyman <hannu.nyman@iki.fi>