The failure is caused by violation of an assertion that checks
AO_double_t variable is 8-byte aligned on x86.

* doc/README.txt (AO_double_t): Add note about required alignment.
* src/atomic_ops/sysdeps/standard_ao_double_t.h (AO_double_t): Add
comment about alignment.
* src/atomic_ops_stack.h (AO_stack_t): Likewise.
* tests/test_atomic_include.template (test_atomicXX): Define old_w, w
local variables as static (as otherwise, e.g., they could have 4-byte
alignment on x86); add comment.

This reverts commit 69c4010c1b3d43e2e179421e27379aaa5aeeb6d8.

The failure is actually caused by the fact that default alignment of
stack on x86 is 4 bytes.
So, another solution should be proposed to fix the issue for other
compilers (and, potentially, other targets).  E.g. do not place
AO_double_t volatile variables on stack.

Passing an unaligned AO_double_t pointer to AO double-wide primitives
results in an undefined behavior of the latter when running on x86 (or
violation of the corresponding assertion on the alignment).
MS VC++/x86 aligns AO_double_t values on a 4-byte boundary by default.
For the proper alignment, __declspec(align(8)) should be applied to
variables defined in the client code (which uses double-wide AO
primitives).  Unfortunately, the attribute cannot be added to
AO_double_t definition itself because the compiler does not allow the
attribute for function arguments.

This patch introduces AO_DOUBLE_ALIGN attribute for use by clients of
the double-wide AO primitives (and, thus, AO_stack clients).
Matters only Visual Studio compiler for X86.
The inner clients (atomic_ops_malloc, test_atomic, test_stack) are
updated to use this attribute.

* doc/README_win32.txt [x86] (AO_DOUBLE_ALIGN): Document.
* src/atomic_ops/sysdeps/generic_pthread.h (AO_DOUBLE_ALIGN): Define
(as empty).
* src/atomic_ops/sysdeps/standard_ao_double_t.h [!_WIN64 && _WIN32
&& !__GNUC__ && _MSC_VER] (AO_DOUBLE_ALIGN): Define as declspec
align(8); document it.
* src/atomic_ops/sysdeps/standard_ao_double_t.h [!AO_DOUBLE_ALIGN]
(AO_DOUBLE_ALIGN): Define as empty (otherwise).
* src/atomic_ops_stack.h [AO_USE_ALMOST_LOCK_FREE && !AO_DOUBLE_ALIGN]
(AO_DOUBLE_ALIGN): Likewise.
* src/atomic_ops_malloc.c (AO_free_list): Use AO_DOUBLE_ALIGN attribute.
* tests/test_stack.c (the_list): Likewise.
* src/atomic_ops_stack.h [!AO_USE_ALMOST_LOCK_FREE] (AO_stack_t):
Document AO_DOUBLE_ALIGN usage (by clients).
* tests/test_atomic_include.template (test_atomicXX): Use
AO_DOUBLE_ALIGN attribute for old_w and w double-wide local variables
(to avoid alignment assertion violation or AO primitives undefined
behavior on x86 if the test code is compiled by VC++).

* tests/test_atomic_include.template (test_atomicXX): Ensure old_w is
always initialized before AO_double_storeXX; add comment about MSan
false warning.

Previously, only AO_and/or/xor and AO_[fetch]_CAS tests (for AO_t)
existed in test_atomic.

* tests/test_atomic_include.template (test_atomicXX): Add minimal
testing of AO_short_compare_and_swapXX, AO_short_orXX, AO_short_xorXX,
AO_short_andXX, AO_short_fetch_compare_and_swapXX,
AO_char_compare_and_swapXX, AO_char_orXX, AO_char_xorXX, AO_char_andXX,
AO_char_fetch_compare_and_swapXX, AO_int_compare_and_swapXX,
AO_int_orXX, AO_int_xorXX, AO_int_andXX,
AO_int_fetch_compare_and_swapXX.

AO_XSIZE_and/or/xor_dd_acquire_read are meaningless and not implemented,
thus their absence is not reported in the tests.

* tests/test_atomic_include.template [!AO_HAVE_orXX] (test_atomicXX):
Do not call MISSING(AO_or) if all AO_HAVE_or* excluding
AO_HAVE_or_dd_acquire_read are not defined.
* tests/test_atomic_include.template [!AO_HAVE_xorXX] (test_atomicXX):
Do not call MISSING(AO_xor) if all AO_HAVE_xor* excluding
AO_HAVE_xor_dd_acquire_read are not defined.
* tests/test_atomic_include.template [!AO_HAVE_andXX] (test_atomicXX):
Do not call MISSING(AO_and) if all AO_HAVE_and* excluding
AO_HAVE_and_dd_acquire_read are not defined.

* src/atomic_ops.h [AO_CAN_EMUL_CAS]: Include emul_cas.h also if
CPPCHECK (to define AO_store_full as AO_store_full_emulation).
* tests/test_atomic_include.template [CPPCHECK] (list_atomicXX,
char_list_atomicXX, short_list_atomicXX, int_list_atomicXX,
double_list_atomicXX): Declare function.
* tests/test_atomic_include.template test_atomicXX (test_atomicXX):
Call list_atomicXX, char_list_atomicXX, short_list_atomicXX,
int_list_atomicXX and double_list_atomicXX if CPPCHECK.

Assertion for v value after fetch_and_sub1(&v) is added.

* tests/test_atomic_include.template (test_atomicXX): Call TA_assert
for s, b, zz values after they are decremented (use volatile pointer to
avoid "condition is always true" compiler warning).

* tests/test_atomic_include.template (test_atomicXX): Treat "x"
variable as volatile one to suppress cppcheck warning that x==13 is
always true.
* tests/test_atomic_include.template (test_atomicXX): Make
TA_assert(x==117) unconditional to suppress cppcheck warning that the
value assigned by x=117 is never used.

Use TA_assert consistently (not assert).

* tests/test_atomic_include.template (test_atomicXX): Replace assert()
calls with TA_assert().