Provide replacement function for strchrnul.

The strchrnul function is a GNU extension and as such is not
available everywhere.

lib/strchrnul.c

@@ -0,0 +1,28 @@
+/*
+ * strchrnul - Incenp.org Notch Library: strchrnul replacement
+ * Copyright (C) 2011 Damien Goutte-Gattat
+ *
+ * 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/>.
+ */
+
+char *
+strchrnul(const char *s, int c)
+{
+    char *p = (char *)s;
+
+    while ( *p != c && *p != '\0' )
+        p += 1;
+
+    return p;
+}

m4/notch.m4

@@ -4,7 +4,7 @@ dnl everywhere, and for which we provide a replacement.
 dnl
 AC_DEFUN([ICP_CHECK_NOTCH_FUNCS],[
 AC_CHECK_HEADERS([err.h], [], [AC_CONFIG_LINKS([err.h:lib/err.compat.h])])
-AC_REPLACE_FUNCS([err])
+AC_REPLACE_FUNCS([err strchrnul])
 AC_CHECK_DECLS([program_invocation_short_name], [],
                [AC_CHECK_FUNCS([getprogname setprogname], [],
                                [AC_LIBOBJ([progname])])],