--- dante-1.4.2/acinclude.m4.orig	2017-01-23 20:28:08.000000000 +0100

+++ dante-1.4.2/acinclude.m4	2017-04-16 11:08:02.385924479 +0200

@@ -1106,6 +1106,8 @@

 dnl test function that tries to determine if a specified errno error exists

 m4_define([checkerrno],

  [AC_MSG_CHECKING(for errno symbol $3)

+  CPPFLAGS_save="$CPPFLAGS"

+  CPPFLAGS="$CPPFLAGS -P"

   AC_PREPROC_IFELSE(

        [AC_LANG_PROGRAM([[#include <errno.h>]],

                         [[

@@ -1117,7 +1119,9 @@

        [AC_MSG_RESULT([OK])

         $1="$$1 $3"

         cat conftest.i | grep errnoval: >>$2],

-       [AC_MSG_RESULT([no])])])

+       [AC_MSG_RESULT([no])])

+  CPPFLAGS="$CPPFLAGS_save"

+])

 AC_DEFUN([L_CHECKERRNO],

  [checkerrno($@)])

@@ -1127,8 +1131,11 @@

 dnl test function that tries to determine if a specified errno error exists

 m4_define([checkgaierror],

  [AC_MSG_CHECKING(for getaddrinfo() error $3)

+  CPPFLAGS_save="$CPPFLAGS"

+  CPPFLAGS="$CPPFLAGS -P"

   AC_PREPROC_IFELSE(

        [AC_LANG_PROGRAM([[

+//#define _GNU_SOURCE 1

 #include <sys/types.h>

 #include <sys/socket.h>

 #include <netdb.h>]],

@@ -1142,7 +1149,9 @@

         $1="$$1 $3"

         AC_DEFINE(HAVE_ERR_$3, 1, [$3 gai error found])

         cat conftest.i | grep gaierrval: >>$2],

-       [AC_MSG_RESULT([no])])])

+       [AC_MSG_RESULT([no])])

+  CPPFLAGS="$CPPFLAGS_save"

+])

 AC_DEFUN([L_CHECKGAIERROR],

  [checkgaierror($@)])