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

diff --cc configure.in
index a13b79c38aca5f63834f96074a43724f19feb265,51f26c3f40ccd4753ff0182850676d2004dc57dc..54d38d5882d3bc1c666c7f0e1d134b2fbb4f7ae4
--- 1/configure.in
--- 2/configure.in
+++ b/configure.in
@@@ -770,14 -770,15 +770,16 @@@ AC_ARG_WITH(libcurl, [AS_HELP_STRING([-
        then
                with_libcurl="yes"
        else
 -              if test -x "$withval"
 +              if test -f "$withval" && test -x "$withval"
                then
                        with_curl_config="$withval"
+                       with_libcurl="yes"
                else if test -x "$withval/bin/curl-config"
                then
                        with_curl_config="$withval/bin/curl-config"
+                       with_libcurl="yes"
                fi; fi
 +              with_libcurl="yes"
        fi; fi
  ],
  [