Workaround Thread Sanitizer (TSan) false positive warnings

Workaround Thread Sanitizer (TSan) false positive warnings

* src/atomic_ops.h [__has_feature && __has_feature(thread_sanitizer)]
(AO_THREAD_SANITIZER): New internal macro.
* src/atomic_ops.h [!AO_ATTR_NO_SANITIZE_THREAD]
(AO_ATTR_NO_SANITIZE_THREAD): Likewise.
* src/atomic_ops/generalize-arithm.h: Regenerate.
* src/atomic_ops/generalize-small.h: Likewise.
* src/atomic_ops/generalize-arithm.template
(AO_XSIZE_fetch_and_add_full, AO_XSIZE_fetch_and_add_acquire,
AO_XSIZE_fetch_and_add_release, AO_XSIZE_fetch_and_add,
AO_XSIZE_and_full, AO_XSIZE_or_full, AO_XSIZE_xor_full): Add
AO_ATTR_NO_SANITIZE_THREAD attribute.
* src/atomic_ops/generalize-small.template (AO_XSIZE_load_read,
AO_XSIZE_load_full, AO_XSIZE_load_acquire, AO_XSIZE_load,
AO_XSIZE_store_write, AO_XSIZE_store, AO_XSIZE_store_release,
AO_XSIZE_store_full: Likewise.
* src/atomic_ops_stack.c [AO_USE_ALMOST_LOCK_FREE]
(AO_stack_push_explicit_aux_release): Likewise.
* src/atomic_ops_stack.c [AO_HAVE_compare_double_and_swap_double]
(AO_stack_push_release, AO_stack_pop_acquire): Likewise.
* tests/test_malloc.c (cons): Likewise.
* src/atomic_ops/sysdeps/gcc/x86.h [AO_GCC_ATOMIC_TEST_AND_SET
&& __clang__ && __x86_64__ && !__ILP32__ && AO_THREAD_SANITIZER]
(AO_SKIPATOMIC_double_compare_and_swap_ANY, AO_SKIPATOMIC_double_load,
AO_SKIPATOMIC_double_load_acquire, AO_SKIPATOMIC_double_store,
AO_SKIPATOMIC_double_store_release): Define; update comment.
* src/atomic_ops_malloc.c [AO_THREAD_SANITIZER] (AO_malloc, AO_free):
Use AO_store/load to write/read log_sz value in object header.
* tests/test_atomic.c (do_junk): New function (declared with
AO_ATTR_NO_SANITIZE_THREAD attribute); multiply junk value by two
different constant values.
* tests/test_atomic.c (test_and_set_thr): Call do_junk() instead of
operating on junk global variable directly.