+# This is quite unpleasant. It turns out that most header checking
+# macros call AC_INCLUDES_DEFAULT. By default AC_INCLUDES_DEFAULT
+# implies AC_HEADER_STDC and a bunch of conditional includes. But
+# these header checks are obsolete as the documentation for
+# AC_HEADER_STDC says. Instead, define AC_INCLUDES_DEFAULT ourselves.
+# The list of headers below is the list from `(autoconf) Default
+# Includes' (filtered by hand for the modern ones rather than the
+# fallbacks). We must include $1 because AC_INCLUDES_DEFAULT is
+# called with an argument giving the check-specific haders.
+m4_define([AC_INCLUDES_DEFAULT],[
+ # include <sys/types.h>
+ # include <sys/stat.h>
+ # include <stdlib.h>
+ # include <stddef.h>
+ # include <string.h>
+ # include <inttypes.h>
+ # include <stdint.h>
+ # include <unistd.h>
+$1
+])
+