Workaround Thread Sanitizer (TSan) false positive warnings (partially)

Workaround Thread Sanitizer (TSan) false positive warnings (partially)

This patch covers only data race false positive warnings reported in
async_set_pht_entry_from_index, GC_clear_stack, GC_invoke_finalizers,
GC_lock, GC_noop1, GC_notify_or_invoke_finalizers, GC_pthread_create,
GC_suspend_handler_inner, I_DONT_HOLD_LOCK.

* finalize.c (GC_should_invoke_finalizers): Add
GC_ATTR_NO_SANITIZE_THREAD.
* mark.c (GC_noop1): Likewise.
* os_dep.c [MPROTECT_VDB && THREADS && AO_HAVE_test_and_set_acquire]
(async_set_pht_entry_from_index): Likewise.
* finalize.c (GC_invoke_finalizers, GC_notify_or_invoke_finalizers):
Call GC_should_invoke_finalizers() instead of
GC_fnlz_roots.finalize_now!=NULL.
* include/private/gc_locks.h [(GC_WIN32_THREADS && !USE_PTHREAD_LOCKS
|| GC_PTHREADS) && GC_ASSERTIONS && THREAD_SANITIZER]
(I_DONT_HOLD_LOCK): Define to TRUE; add comment.
* include/private/gc_locks.h [!GC_ALWAYS_MULTITHREADED
&& THREAD_SANITIZER] (set_need_to_lock): Do not set GC_need_to_lock if
already set; add comment.
* include/private/gc_priv.h [!GC_ATTR_NO_SANITIZE_THREAD]
(GC_ATTR_NO_SANITIZE_THREAD): New macro.
* include/private/gcconfig.h [__has_feature &&
__has_feature(thread_sanitizer)] (THREAD_SANITIZER): Define.
* misc.c [THREADS] (next_random_no): New static function (with
GC_ATTR_NO_SANITIZE_THREAD).
* pthread_stop_world.c [!GC_OPENBSD_UTHREADS && !NACL]
(update_last_stop_count): Likewise.
* pthread_support.c [THREAD_SANITIZER && (USE_SPIN_LOCK
|| !NO_PTHREAD_TRYLOCK)] (is_collecting): Likewise.
* pthread_support.c [USE_SPIN_LOCK] (set_last_spins_and_high_spin_max,
reset_spin_max): Likewise.
* misc.c [THREADS] (GC_clear_stack): Remove random_no static variable;
use next_random_no() instead of ++random_no%13.
* pthread_stop_world.c [!GC_OPENBSD_UTHREADS && !NACL]
(GC_suspend_handler_inner): Call update_last_stop_count() instead of
me->stop_info.last_stop_count=my_stop_count.
* pthread_support.c [USE_SPIN_LOCK || !NO_PTHREAD_TRYLOCK] (SPIN_MAX):
Define only if not yet.
* pthread_support.c [USE_SPIN_LOCK || !NO_PTHREAD_TRYLOCK]
(GC_collecting): Initialize to FALSE instead of 0.
* pthread_support.c [!(THREAD_SANITIZER && (USE_SPIN_LOCK
|| !NO_PTHREAD_TRYLOCK))] (is_collecting): Define as a macro.
* pthread_support.c [USE_SPIN_LOCK] (low_spin_max, high_spin_max,
spin_max, last_spins): Move definition out of GC_lock().
* pthread_support.c (GC_lock): Use is_collecting(),
set_last_spins_and_high_spin_max() and reset_spin_max().