fix ftbfs with GCC 5 (real issue in dee)

dee-transaction.c: In function 'dee_transaction_get_first_iter':
dee-transaction.c:236:59: error: logical not is only applied to the left hand side of comparison [-Werror=logical-not-parentheses]
 #define journal_iter_is_removed(jiter) jiter->change_type == CHANGE_TYPE_REMOVE
                                                           ^
/usr/include/glib-2.0/glib/gmacros.h:319:8: note: in definition of macro '_G_BOOLEAN_EXPR'
    if (expr) \
        ^
/usr/include/glib-2.0/glib/gtestutils.h:106:49: note: in expansion of macro 'G_LIKELY'
                                              if G_LIKELY (expr) ; else \
                                                 ^
dee-transaction.c:1245:7: note: in expansion of macro 'g_assert'
       g_assert (!journal_iter_is_removed (jiter));
       ^
dee-transaction.c:1245:18: note: in expansion of macro 'journal_iter_is_removed'
       g_assert (!journal_iter_is_removed (jiter));
                  ^
cc1: all warnings being treated as errors
Makefile:791: recipe for target 'libdee_1_0_la-dee-transaction.lo' failed
make[4]: *** [libdee_1_0_la-dee-transaction.lo] Error 1