Update kernel version in syscall-names.list to 4.17.

As far as I can tell, Linux 4.17 does not add any new syscalls; this
patch updates the version number in syscall-names.list to reflect that
it's still current for 4.17.

Tested for x86_64-linux-gnu with build-many-glibcs.py.

	* sysdeps/unix/sysv/linux/syscall-names.list: Update kernel
	version to 4.17.