Fix handling of len and lenof as names

For compatibility with programs written for older Snowball versions
len and lenof stop being tokens if declared as names.  However this
code didn't work correctly if the tokeniser's name buffer didn't have
enough space for the name (i.e. 3 or 5 elements respectively).

compiler/analyser.c

@@ -268,7 +268,7 @@ static void read_names(struct analyser * a, int type) {
                 static const symbol c_len_lit[] = {
                     'l', 'e', 'n'
                 };
-                MOVE_TO_B(t->b, c_len_lit);
+                t->b = MOVE_TO_B(t->b, c_len_lit);
                 goto handle_as_name;
             }
             case c_lenof: {
@@ -279,7 +279,7 @@ static void read_names(struct analyser * a, int type) {
                 static const symbol c_lenof_lit[] = {
                     'l', 'e', 'n', 'o', 'f'
                 };
-                MOVE_TO_B(t->b, c_lenof_lit);
+                t->b = MOVE_TO_B(t->b, c_lenof_lit);
                 goto handle_as_name;
             }
             case c_name: