Upgrade libatomic_ops to 7.6.4
Major changes since v7.6.0:
- Eliminate compiler warnings
- Eliminate data race in cons() of test_malloc
- Fix 'bad register name %sil' assembler error (GCC-4.4/x86)
- Fix 'doc' files installation folder
- Fix AO_malloc for sizes near CHUNK_SIZE
- Fix memory leak in test_malloc
- Fix public headers inclusion from clients C++ code
- Fix size value wrap around in AO_malloc_large
- Fix test failures for Clang-3.8 and older (Aarch64)
- Fix test_atomic failure caused unaligned AO_double_t access (x86)
- Implement fetch-CAS for s390[x] (gcc)
- Support AIX/ppc, MIPS rel6, n32 ABI for mips64, RISC-V
- Update README about bugs reporting and new releases notification
- Use built-in atomics for load/store/CAS for Clang by default (Aarch64)
- Use GCC atomic intrinsics for Hexagon (clang 3.9+)
- Use LLD and SCD instructions on mips64
Reported by: Ivan Maidanski <ivmai@mail.ru> (by email)