Update syscall-names.list for Linux 5.7

[Dmitry V. Levin]

On Mon, Jun 15, 2020 at 08:17:53PM +0000, Joseph Myers wrote:
> Linux 5.7 has no new syscalls.  Update the version number in
> syscall-names.list to reflect that it is still current for 5.7.

LGTM, thanks,


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