collectd: update to 5.5.0

Update collectd, base of Luci statistics, to 5.5.0.

Patches have been refreshed.
write-graphite plugin is now enabled. (see #1351)

I have compile-tested all plugins with ar71xx,
and real-life tested the following plugins:
Conntrack, Processor (CPU), DNS, Interfaces, Wireless, System Load,
Memory, Ping, Uptime

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

utils/collectd/patches/003-remove-werror.patch

@@ -1,14 +1,14 @@
 --- a/src/Makefile.am
 +++ b/src/Makefile.am
-@@ -4,7 +4,7 @@ SUBDIRS += liboconfig
- endif
+@@ -7,7 +7,7 @@ SUBDIRS += daemon
+ PLUGIN_LDFLAGS = -module -avoid-version -export-symbols-regex '\<module_register\>'
  
  if COMPILER_IS_GCC
 -AM_CFLAGS = -Wall -Werror
 +AM_CFLAGS = -Wall
  endif
  
- AM_CPPFLAGS = -DPREFIX='"${prefix}"'
+ AM_CPPFLAGS = -I$(srcdir)/daemon
 --- a/src/libcollectdclient/Makefile.am
 +++ b/src/libcollectdclient/Makefile.am
 @@ -1,7 +1,7 @@