mq_tree_size(), mq_tree_position(): Fix conditional expressions

Fixes:

      CC       src/marquee-notebook.o
    In file included from src/notebook.c:29:0:
    src/notebook.c: In function ‘mq_notebook_get_n_pages’:
    src/tree.h:67:70: warning: pointer/integer type mismatch in conditional expression
     #define mq_tree_size(node)     ((node) ? (((MqTree *) (node))->size) : NULL)
                                                                          ^
    src/notebook.c:253:9: note: in expansion of macro ‘mq_tree_size’
      return mq_tree_size(MQ_TREE(notebook->tree));
             ^
    src/notebook.c:253:2: warning: return makes integer from pointer without a cast
      return mq_tree_size(MQ_TREE(notebook->tree));
      ^

0 files changed, 0 insertions, 0 deletions