Add native Windows binary for bison.

bison/src/bison/2.4.1/bison-2.4.1-src/m4/m4.m4

+# Copyright 2000 Free Software Foundation, Inc.
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+# BISON_PROG_GNU_M4
+# -----------------
+# Check for GNU m4, at least 1.3 (supports frozen files).
+AC_DEFUN([BISON_PROG_GNU_M4],
+[AC_PATH_PROGS(M4, gm4 gnum4 m4, m4)
+AC_CACHE_CHECK(whether m4 supports frozen files, ac_cv_prog_gnu_m4,
+[ac_cv_prog_gnu_m4=no
+if test x"$M4" != x; then
+  case `$M4 --help < /dev/null 2>&1` in
+    *reload-state*) ac_cv_prog_gnu_m4=yes ;;
+  esac
+fi])])