(init_intervals, make_interval,
mark_interval, mark_interval_tree): New functions conditionally
defined.
(make_uninit_string): Call INITIALIZE_INTERVAL.
(INIT_INTERVALS, UNMARK_BALANCE_INTERVALS, MARK_INTERVAL_TREE):
New macros, conditionally defined.
(mark_object): Call MARK_INTERVAL_TREE in case Lisp_String.
(gc_sweep): If text properties are in use, place all unmarked
intervals on the free list. Call UNMARK_BALANCE_INTERVALS on
`buffer->intervals' when unmarking `buffer'.
(compact_strings): Include INTERVAL_PTR_SIZE in calculation for
target of bcopy when relocating strings.
(init_alloc_once): Call INIT_INTERVALS.
(make_pure_string): Include INTERVAL_PTR_SIZE in calculation of
`size'.
value, function, and property list rather than before; this way,
symbols' names are readable, giving us a chance to detect some
kinds of heap corruption.
signal handler. The original bug is probably gone, the test
wasn't written portably, and it should probably go somewhere else
anyway - say, funcall or eval.
