Fixes behavior of 'x' in normal mode

After 'x' is used to delete a character at the end of a line the cursor
should be repositioned at the last character, i.e. repeatedly pressing
'x' in normal mode should delete the entire string.

src/reader.cpp

@@ -2746,6 +2746,9 @@ const wchar_t *reader_readline(int nchars) {
                 if (el->position < el->size()) {
                     update_buff_pos(el, el->position + 1);
                     remove_backward();
+                    if (el->position > 0 && el->position == el->size()) {
+                        update_buff_pos(el, el->position - 1);
+                    }
                 }
                 break;
             }