Update syscall lists for Linux 5.5.

Linux 5.5 has no new syscalls to add to syscall-names.list, but it
does newly enable the clone3 syscall for AArch64.  This patch updates
the kernel version listed in syscall-names.list and regenerates the
AArch64 arch-syscall.h.

Tested with build-many-glibcs.py.

(cherry picked from commit 5828bc45)