# AC_GNU_SOURCE
# --------------
AC_DEFUN([AC_GNU_SOURCE],
[AH_VERBATIM([_GNU_SOURCE],
[/* Enable GNU extensions on systems that have them.  */
#ifndef _GNU_SOURCE
# undef _GNU_SOURCE
#endif])dnl
AC_BEFORE([$0], [AC_COMPILE_IFELSE])dnl
AC_BEFORE([$0], [AC_RUN_IFELSE])dnl
AC_DEFINE([_GNU_SOURCE])
])