-#serial 1
-# Make sure _GNU_SOURCE is defined where necessary: as early as possible
-# for configure-time tests, as well as for every source file that includes
-# config.h.
-
-# From Jim Meyering.
-
-AC_DEFUN(AC__GNU_SOURCE,
-[
- # Make sure that _GNU_SOURCE is defined for all subsequent
- # configure-time compile tests.
- # This definition must be emitted (into confdefs.h) before any
- # test that involves compilation.
- AC_DEFINE(_GNU_SOURCE_KLUDGE, [1
+# AC_GNU_SOURCE
+# --------------
+AC_DEFUN([AC_GNU_SOURCE],
+[AH_VERBATIM([_GNU_SOURCE],
+[/* Enable GNU extensions on systems that have them. */