* fixed bug tracefile.c: tage_alloc() as encountered in bug 5857

*   Asserted tage->page != NULL in tage_free; how could it ever be otherwise?

*   Moved what seemed like an obviously incorrect assertion in trace_get_tage()
    that tcd_pages was not empty into the "debug daemon buffer overflowed"
    branch.

    Someone should review this change; I'm flagging it in bug 5857