Update syscall lists for Linux 5.5

[Florian Weimer]

* Joseph Myers:

> 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.

Have you been able to use build-many-glibcs.py for the update?  Does
the update-syscalls subcommand fit your needs?