* configure.in: Check the protos of strchr ans strspn.

Replace strchr if needed.
* src/system.h: Provide the protos of strchr, strspn and memchr if
missing.
* lib/strchr.c: New.
* src/reader.c (symbols_save): Use strchr.

lib/strchr.c

@@ -0,0 +1,32 @@
+/* Copyright (C) 2001 Free Software Foundation, Inc.
+
+   This program is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Library General Public License
+   as published by the Free Software Foundation; either version 2 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
+   Library General Public License for more details.
+
+   You should have received a copy of the GNU Library General Public
+   License along with this program; see the file COPYING.LIB.  If not,
+   write to the Free Software Foundation, Inc., 59 Temple Place -
+   Suite 330, Boston, MA 02111-1307, USA.  */
+
+#if HAVE_CONFIG_H
+# include <config.h>
+#endif
+
+#if HAVE_STRING_H
+# include <string.h>
+#else
+# include <strings.h>
+#endif
+
+char *
+strchr (const char *s, int c)
+{
+  return index (s, c);
+}