Merge branch 'pull/collectd-4.1' into collectd-4.1

diff --cc configure.in
index 8544ca4,252d16f..6829954
--- 1/configure.in
--- 2/configure.in
+++ b/configure.in
@@@ -1431,10 -1425,15 +1425,16 @@@ the
        SAVE_CFLAGS=$CFLAGS
        CFLAGS="$CFLAGS $with_libnetlink_cflags"
  
-       AC_CHECK_HEADERS(iproute/libnetlink.h, [], [with_libnetlink="no (iproute/libnetlink.h not found)"],
+       with_libnetlink="no (libnetlink.h not found)"
+ 
+       AC_CHECK_HEADERS(libnetlink.h iproute/libnetlink.h linux/libnetlink.h,
+       [
+        with_libnetlink="yes"
+        break
+       ], [],
  [#include <stdio.h>
  #include <sys/types.h>
 +#include <asm/types.h>
  #include <sys/socket.h>
  #include <linux/netlink.h>
  #include <linux/rtnetlink.h>])