Add new macro (AO_PREFER_GENERALIZED) to favor generalized primitives

Add new macro (AO_PREFER_GENERALIZED) to favor generalized primitives
over direct assembly-based ones

* configure.ac (AO_PREFER_GENERALIZED): New AC template.
* src/atomic_ops/sysdeps/armcc/arm_v6.h (AO_test_and_set,
AO_HAVE_test_and_set, AO_fetch_and_add, AO_HAVE_fetch_and_add,
AO_fetch_and_add1, AO_HAVE_fetch_and_add1, AO_fetch_and_sub1,
AO_HAVE_fetch_and_sub1): Do not define if AO_PREFER_GENERALIZED.
* src/atomic_ops/sysdeps/gcc/arm.h (AO_test_and_set,
AO_HAVE_test_and_set, AO_fetch_and_add, AO_HAVE_fetch_and_add,
AO_fetch_and_add1, AO_HAVE_fetch_and_add1, AO_fetch_and_sub1,
AO_HAVE_fetch_and_sub1): Likewise.
* src/atomic_ops/sysdeps/gcc/avr32.h (AO_test_and_set_full,
AO_HAVE_test_and_set_full): Likewise.
* src/atomic_ops/sysdeps/gcc/hexagon.h (AO_fetch_and_add,
AO_HAVE_fetch_and_add, AO_test_and_set, AO_HAVE_test_and_set):
Likewise.
* src/atomic_ops/sysdeps/gcc/ia64.h (AO_fetch_and_add1_acquire,
AO_HAVE_fetch_and_add1_acquire, AO_fetch_and_add1_release,
AO_HAVE_fetch_and_add1_release, AO_fetch_and_sub1_acquire,
AO_HAVE_fetch_and_sub1_acquire, AO_fetch_and_sub1_release,
AO_HAVE_fetch_and_sub1_release, AO_int_fetch_and_add1_acquire,
AO_HAVE_int_fetch_and_add1_acquire, AO_int_fetch_and_add1_release,
AO_HAVE_int_fetch_and_add1_release, AO_int_fetch_and_sub1_acquire,
AO_HAVE_int_fetch_and_sub1_acquire, AO_int_fetch_and_sub1_release,
AO_HAVE_int_fetch_and_sub1_release): Likewise.
* src/atomic_ops/sysdeps/gcc/powerpc.h (AO_test_and_set,
AO_HAVE_test_and_set, AO_test_and_set_acquire,
AO_HAVE_test_and_set_acquire, AO_test_and_set_release,
AO_HAVE_test_and_set_release, AO_test_and_set_full,
AO_HAVE_test_and_set_full): Likewise.
* src/atomic_ops/sysdeps/gcc/x86.h (AO_fetch_and_add_full,
AO_HAVE_fetch_and_add_full, AO_and_full, AO_HAVE_and_full,
AO_or_full, AO_HAVE_or_full, AO_xor_full, AO_HAVE_xor_full): Likewise.
* src/atomic_ops/sysdeps/gcc/x86_64.h (AO_fetch_and_add_full,
AO_HAVE_fetch_and_add_full, AO_and_full, AO_HAVE_and_full, AO_or_full,
AO_HAVE_or_full, AO_xor_full, AO_HAVE_xor_full): Likewise.
* src/atomic_ops/sysdeps/hpc/ia64.h (AO_fetch_and_add1_acquire,
AO_HAVE_fetch_and_add1_acquire, AO_fetch_and_add1_release,
AO_HAVE_fetch_and_add1_release, AO_fetch_and_sub1_acquire,
AO_HAVE_fetch_and_sub1_acquire, AO_fetch_and_sub1_release,
AO_HAVE_fetch_and_sub1_release): Likewise.
* src/atomic_ops/sysdeps/ibmc/powerpc.h (AO_test_and_set_acquire,
AO_HAVE_test_and_set_acquire, AO_test_and_set_release,
AO_HAVE_test_and_set_release, AO_test_and_set_full,
AO_HAVE_test_and_set_full): Likewise.
* src/atomic_ops/sysdeps/icc/ia64.h (AO_fetch_and_add1_acquire,
AO_HAVE_fetch_and_add1_acquire, AO_fetch_and_add1_release,
AO_HAVE_fetch_and_add1_release, AO_fetch_and_sub1_acquire,
AO_HAVE_fetch_and_sub1_acquire, AO_fetch_and_sub1_release,
AO_HAVE_fetch_and_sub1_release): Likewise.
* src/atomic_ops/sysdeps/msftc/x86_64.h (AO_fetch_and_add_full,
AO_HAVE_fetch_and_add_full, AO_fetch_and_add1_full,
AO_HAVE_fetch_and_add1_full, AO_fetch_and_sub1_full,
AO_HAVE_fetch_and_sub1_full): Likewise.
* src/atomic_ops/sysdeps/sunc/x86.h (AO_fetch_and_add_full,
AO_HAVE_fetch_and_add_full, AO_and_full, AO_HAVE_and_full,
AO_or_full, AO_HAVE_or_full, AO_xor_full, AO_HAVE_xor_full): Likewise.
* src/atomic_ops/sysdeps/sunc/x86_64.h (AO_fetch_and_add_full,
AO_HAVE_fetch_and_add_full, AO_and_full, AO_HAVE_and_full,
AO_or_full, AO_HAVE_or_full, AO_xor_full, AO_HAVE_xor_full): Likewise.
* src/atomic_ops/sysdeps/gcc/arm.h (AO_test_and_set_full,
AO_HAVE_test_and_set_full): Do not define if AO_PREFER_GENERALIZED
(but only in case of ARMv6+).
* src/atomic_ops/sysdeps/msftc/common32_defs.h (_InterlockedIncrement,
_InterlockedDecrement, _InterlockedExchangeAdd): Do not declare
intrinsic if both AO_PREFER_GENERALIZED and AO_ASSUME_WINDOWS98.
* src/atomic_ops/sysdeps/msftc/common32_defs.h (AO_fetch_and_add_full,
AO_HAVE_fetch_and_add_full, AO_fetch_and_add1_full,
AO_HAVE_fetch_and_add1_full, AO_fetch_and_sub1_full,
AO_HAVE_fetch_and_sub1_full): Do not define if both
AO_PREFER_GENERALIZED and AO_ASSUME_WINDOWS98.
* src/atomic_ops/sysdeps/msftc/x86_64.h (_InterlockedIncrement64,
_InterlockedDecrement64, _InterlockedExchangeAdd64): Do not declare
intrinsic if AO_PREFER_GENERALIZED.