collectd: Update to 5.4.1

-update collectd to the current release 5.4.1
-fix sigrok glib check (upstream patch after 5.4.1)

Note:
Changes are required also to luci-statistics in Luci source.
Patch in http://patchwork.openwrt.org/patch/5303/

Signed-off-by: Hannu Nyman <hannu.nyman@iki.fi>

Additional notes:
Collectd, the backbone of Luci statistics module, has been updated already to 5.4.1, while Openwrt is still with 4.10.8.

5.0-5.4 branches have been released in 2011-2013 and the last Collectd release in January 2014 only contained 5.4.1. 4.10.x is being "phased out" and new commits have been made only rarely. No 4.10.x release for ages.

My ar71xx/wndr3700 build has been using 5.4.1 since March (and used 5.3.1 long before that).

I have compile-tested (with ar71xx) all collectd modules, and I have verified the real-life functionality of the following plugins: Conntrack, CPU/Processor, DNS, Interfaces, Memory, Ping, Processes, TCP Connections, System Load, Uptime, Wireless.


The version bump requires changes both to "collectd" in the packages feed and to "luci-statistics" in the luci feed, as some of the data items have changed name or file structure.


Collectd:
Explanation of main changes in the patches for collectd in packages feed:

Patches to be removed:

- 120-fix_kernel_2.6.37.patch is unnecessary. The file to be patched has been 
removed upstream.

- 130-timeleft-max.patch is included upstream. Patch removed.
http://git.verplant.org/?p=collectd.git;a=commitdiff;h=d5b09f2bb673ac9396da52b85bcbd16c98b3d633

Changed patches:

- 003-remove-werror.patch: Quilt choked on some -Werror related changes, so I removed them.

- 900-add-iwinfo-plugin.patch: Changed to patch configure.ac instead of configure.in

New patches:

- 140-fix-fqdnlookup.patch : FQDNLookup option has been turned on by default since 5.1. If that option is enabled, it causes collectd to refuse to start in a basic Openwrt box as typically a fully qualified domain name does not exist for the router. (That error related can only be properly seen when console is used to start collectd. Otherwise Luci statistics collectd simply dies immediately after starting it.) That option should be false by default. I included a new patch 140-fix-fqdnlookup.patch to turn the option off by default.
http://git.verplant.org/?p=collectd.git;a=commit;h=e58f85bb68b4c45130bb6fdf40b51db95d2b71e5

- 150-fix-interface-af-link : a FreeBSD10-specific change broke build for me, so I reverted the change.
http://git.verplant.org/?p=collectd.git;a=commitdiff;h=645dadb3fcc466e8880fda4eb23b21ad433631fc

- 905-fix-sigrok-upstream-patch-post-541: libsigrok checks for a glib-related macro that breaks configure. Use later upstream patch ( http://git.verplant.org/?p=collectd.git;a=commit;h=5bdc5d3ede2e1fad94dd7ebf6f76103201c39c3c ) to bypass the invalid macro. I have also added a disabling option in Makefile.


Luci:
Data presentation in luci-statistics requires three changes in the Luci sources:

-conntrack result data has changed name from "entropy" to "value".
-ping result data has changed name from "ping" to "value".
http://git.verplant.org/?p=collectd.git;a=commitdiff;h=77a6905147798210ec17173bd5e4410adcc3a112 

-interface plugin has changed rrd data file structure so that the plugin 
instances (=interfaces) have separate data files. Luci needs to draw the 
graph for each plugin instance, not for each data instance.
http://git.verplant.org/?p=collectd.git;a=commitdiff;h=cc3640ba512862cd5745446f1f1a997dd4344454 

Patch for Luci has been submitted in May 2014 and can be found at http://patchwork.openwrt.org/patch/5303/

Applying this pull request requires somebody like @jow with write access also to Luci code.