terminate longopt list to prevent crashes on FreeBSD

tools/osmpbf-outline.cpp

@@ -90,6 +90,7 @@ int main(int argc, char *argv[]) {
 
     static struct option long_options[] = {
         {"color",                no_argument, 0, 'c'},
+        {0,0,0,0}
     };
 
     while (1) {