dnl check for fields in a structure
dnl
dnl AC_HAVE_STRUCT_FIELD(struct, field, headers)

AC_DEFUN(AC_HAVE_STRUCT_FIELD, [
define(cache_val, translit(ac_cv_type_$1_$2, [A-Z ], [a-z_]))
AC_CACHE_CHECK([for $2 in $1], cache_val,[
AC_TRY_COMPILE([$3],[$1 x; x.$2;],
cache_val=yes,
cache_val=no)])
if test "$cache_val" = yes; then
	define(foo, translit(HAVE_$1_$2, [a-z ], [A-Z_]))
	AC_DEFINE(foo, 1, [Define if $1 has field $2.])
	undefine(foo)
fi
undefine(cache_val)
])