Add minimal-ish example of what causes deadcode in smtprc.

Author: vesalvojdani

tests/regression/03-practical/27-charptr_null.c

@@ -0,0 +1,33 @@
+#include <string.h>
+#include <assert.h>
+#include <stdlib.h>
+#include <stdio.h>
+
+struct options
+{
+    char *ip_range;
+};
+
+struct options o;
+
+int get_ip_range(int *iprange)
+{
+    char *r = iprange;
+
+    while (*r++)
+    {
+        *r = '\0';
+        assert(1);
+    }
+
+    return (0);
+}
+
+int main()
+{
+    char *optarg = "was from unistd.h";
+    o.ip_range = malloc((strlen(optarg) + 1) * sizeof(char));
+    strncpy(o.ip_range, optarg, strlen(optarg));
+    o.ip_range[strlen(optarg)] = '\0';
+    get_ip_range(o.ip_range);
+}