Fix asm constraint of compare_and_swap for clang-3.1/mips
(Apply commit 3e4c369 from 'master' branch.)

* src/atomic_ops/sysdeps/gcc/mips.h (AO_compare_and_swap): Use "+m"
asm constraint for *addr instead of "+R" (the letter is unsupported
by clang3.1 resulting in "invalid output constraint in asm" error).

Conflicts:

    src/atomic_ops/sysdeps/gcc/mips.h
Fix asm constraint of CAS memory operand for gcc/alpha

* src/atomic_ops/sysdeps/gcc/alpha.h (AO_compare_and_swap): Use "+m"
asm constraint for *addr instead of "=m" (because the value pointed by
addr is read and written by the code).
Fix asm constraints of primitives in sunc/x86.h
(Apply commit 31df7fa from 'master' branch.)

* src/atomic_ops/sysdeps/sunc/x86.h (AO_fetch_and_add_full,
AO_char_fetch_and_add_full, AO_short_fetch_and_add_full, AO_or_full,
AO_test_and_set_full,
AO_compare_and_swap_full): Use "+m" asm constraint for *addr instead
of "=m" (because the value pointed by addr is read and written by the
code).

Conflicts:

    src/atomic_ops/sysdeps/sunc/x86.h
Fix generalized fetch_and_add function

* src/atomic_ops/generalize-small.template (AO_XSIZE_fetch_and_add):
Do not use AO_EXPECT_FALSE (since defined only in v7.3+).
* src/atomic_ops/generalize-small.h: Regenerate.
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