Implement char CAS and char/short add for msftc X86[_64] (VS 2013+)

Implement char CAS and char/short add for msftc X86[_64] (VS 2013+)

* src/atomic_ops/sysdeps/msftc/common32_defs.h [_MSC_VER>=1800]
(_InterlockedCompareExchange8): Declare intrinsic.
* src/atomic_ops/sysdeps/msftc/common32_defs.h [_MSC_VER>=1800
&& !AO_PREFER_GENERALIZED && !_M_ARM] (_InterlockedExchangeAdd16,
_InterlockedExchangeAdd8): Likewise.
* src/atomic_ops/sysdeps/msftc/x86_64.h [_MSC_VER>=1800]
(_InterlockedCompareExchange8): Likewise.
* src/atomic_ops/sysdeps/msftc/x86_64.h [_MSC_VER>=1800
&& !AO_PREFER_GENERALIZED] (_InterlockedExchangeAdd16,
_InterlockedExchangeAdd8): Likewise.
* src/atomic_ops/sysdeps/msftc/common32_defs.h [_MSC_VER>=1800]
(AO_char_fetch_compare_and_swap_full): Implement using intrinsic.
* src/atomic_ops/sysdeps/msftc/common32_defs.h [_MSC_VER>=1800
&& !AO_PREFER_GENERALIZED && !_M_ARM] (AO_char_fetch_and_add_full,
AO_short_fetch_and_add_full): Likewise.
* src/atomic_ops/sysdeps/msftc/x86_64.h [_MSC_VER>=1800]
(AO_char_fetch_compare_and_swap_full): Likewise.
* src/atomic_ops/sysdeps/msftc/x86_64.h [_MSC_VER>=1800
&& !AO_PREFER_GENERALIZED] (AO_char_fetch_and_add_full,
AO_short_fetch_and_add_full): Likewise.
* src/atomic_ops/sysdeps/msftc/x86.h [!AO_NO_ASM_XADD]
(AO_char_fetch_and_add_full, AO_short_fetch_and_add_full): Do not
define if AO_HAVE_char_fetch_and_add_full.
* src/atomic_ops/sysdeps/msftc/x86_64.h [AO_ASM_X64_AVAILABLE]
(AO_char_fetch_and_add_full, AO_short_fetch_and_add_full): Do not use
asm-based implementation if _MSC_VER>=1800.