-based on http://github.com/mcr/libpcap/commit/d1a3a92fab103210ab5f61780a731bce9a8909b5
-diff -urNp -x '*.orig' arpwatch-2.1a15.org/aclocal.m4 arpwatch-2.1a15/aclocal.m4
---- arpwatch-2.1a15.org/aclocal.m4 2021-05-09 14:37:46.275738586 +0200
-+++ arpwatch-2.1a15/aclocal.m4 2021-05-09 14:37:46.332408198 +0200
-@@ -23,29 +23,22 @@ dnl LBL autoconf macros
- dnl
-
- dnl
--dnl Determine which compiler we're using (cc or gcc)
--dnl If using gcc, determine the version number
--dnl If using cc, require that it support ansi prototypes
--dnl If using gcc, use -O2 (otherwise use -O)
--dnl If using cc, explicitly specify /usr/local/include
--dnl
--dnl usage:
--dnl
-+dnl Do whatever AC_LBL_C_INIT work is necessary before using AC_PROG_CC.
- dnl AC_LBL_C_INIT(copt, incls)
- dnl
--dnl results:
-+dnl It appears that newer versions of autoconf (2.64 and later) will,
-+dnl if you use AC_TRY_COMPILE in a macro, stick AC_PROG_CC at the
-+dnl beginning of the macro, even if the macro itself calls AC_PROG_CC.
-+dnl See section 20.8 "Expanded Before Required" in the Autoconf
-+dnl documentation.
-+dnl
-+dnl This causes a steaming heap of fail in our case, as we were, in
-+dnl AC_LBL_C_INIT, doing the tests we now do in AC_LBL_C_PREPARE,
-+dnl calling AC_PROG_CC, and then doing the tests we now do in
-+dnl AC_LBL_C_INIT.
- dnl
--dnl $1 (copt set)
--dnl $2 (incls set)
--dnl CC
--dnl LDFLAGS
--dnl LBL_CFLAGS
--dnl
--AC_DEFUN(AC_LBL_C_INIT,
-- [AC_PREREQ(2.12)
-- AC_BEFORE([$0], [AC_PROG_CC])
-- AC_BEFORE([$0], [AC_LBL_FIXINCLUDES])
-- AC_BEFORE([$0], [AC_LBL_DEVEL])
-+AC_DEFUN(AC_LBL_C_INIT_BEFORE_CC,
-+[
- AC_ARG_WITH(gcc, [ --without-gcc don't use gcc])
- $2=""
- if test "${srcdir}" != "." ; then
-@@ -70,7 +63,32 @@ AC_DEFUN(AC_LBL_C_INIT,
- CC=cc
- export CC
- fi
-- AC_PROG_CC
-+])
-+
-+dnl
-+dnl Determine which compiler we're using (cc or gcc)
-+dnl If using gcc, determine the version number
-+dnl If using cc, require that it support ansi prototypes
-+dnl If using gcc, use -O2 (otherwise use -O)
-+dnl If using cc, explicitly specify /usr/local/include
-+dnl
-+dnl usage:
-+dnl
-+dnl AC_LBL_C_INIT(copt, incls)
-+dnl
-+dnl results:
-+dnl
-+dnl $1 (copt set)
-+dnl $2 (incls set)
-+dnl CC
-+dnl LDFLAGS
-+dnl ac_cv_lbl_gcc_vers
-+dnl LBL_CFLAGS
-+dnl
-+AC_DEFUN(AC_LBL_C_INIT,
-+ [AC_PREREQ(2.50)
-+ AC_BEFORE([$0], [AC_LBL_FIXINCLUDES])
-+ AC_BEFORE([$0], [AC_LBL_DEVEL])
- if test "$GCC" != yes ; then
- AC_MSG_CHECKING(that $CC handles ansi prototypes)
- AC_CACHE_VAL(ac_cv_lbl_cc_ansi_prototypes,
-diff -urNp -x '*.orig' arpwatch-2.1a15.org/configure.in arpwatch-2.1a15/configure.in
---- arpwatch-2.1a15.org/configure.in 2006-06-21 22:34:29.000000000 +0200
-+++ arpwatch-2.1a15/configure.in 2021-05-09 14:37:46.332408198 +0200
-@@ -16,6 +16,8 @@ if test -z "$PWD" ; then
- PWD=`pwd`
- fi
-
-+AC_LBL_C_INIT_BEFORE_CC(V_CCOPT, V_INCLS)
-+AC_PROG_CC
- AC_LBL_C_INIT(V_CCOPT, V_INCLS)
-
- AC_CHECK_HEADERS(fcntl.h memory.h)