Mark packed structure element used with atomic operation aligned.
Test for mprotect failure in dl-load.c (bug 12492).
Consistently use page_shift in sysdeps/unix/sysv/linux/mmap64.c.
Add GLRO(dl_hwcap2) for new AT_HWCAP2 auxv_t a_type.
PowerPC: Define AT_HWCAP2 bits and AT_HWCAP2 handling for POWER8.
Skip SSE4.2 versions on Intel Silvermont

SSE2/SSSE3 versions are faster than SSE4.2 versions on Intel Silvermont.
Add more NEWS items for 2.18.