aarch64: Update bits/hwcap.h for Linux 4.15.

Define new HWCAP bits and add their name to dl-procinfo.c following
the linux definitions. Synchronizing with v4.15-rc8 version of linux,
these are not expected to change before the 4.15 release.

	* sysdeps/unix/sysv/linux/aarch64/bits/hwcap.h (HWCAP_SHA3): Define.
	(HWCAP_SM3, HWCAP_SM4, HWCAP_ASIMDDP, HWCAP_SHA512, HWCAP_SVE): Define.
	* sysdeps/unix/sysv/linux/aarch64/dl-procinfo.c
	(_dl_aarch64_cap_flags): Update.
	(_DL_HWCAP_COUNT): Update.