Add asm-based char/short/int CAS implementation for gcc/x86[_64]

Add asm-based char/short/int CAS implementation for gcc/x86[_64]

* src/atomic_ops/sysdeps/gcc/x86.h [!AO_GCC_ATOMIC_TEST_AND_SET]
(AO_char_and_full, AO_char_or_full, AO_char_xor_full, AO_short_and_full,
AO_short_or_full, AO_short_xor_full): Do not define if
AO_PREFER_GENERALIZED.
* src/atomic_ops/sysdeps/gcc/x86.h [!AO_GCC_ATOMIC_TEST_AND_SET]
(AO_char_fetch_compare_and_swap_full,
AO_short_fetch_compare_and_swap_full): Implement.
* src/atomic_ops/sysdeps/gcc/x86.h [!AO_GCC_ATOMIC_TEST_AND_SET
&& __x86_64__ && !__ILP32__] (AO_int_fetch_compare_and_swap_full):
Likewise.
* src/atomic_ops/sysdeps/gcc/x86.h [!AO_GCC_ATOMIC_TEST_AND_SET
&& __x86_64__ && !__ILP32__] (AO_int_fetch_and_add_full,
AO_int_and_full, AO_int_or_full, AO_int_xor_full): Do not define if
AO_PREFER_GENERALIZED.