[BUG] kexec-tools blows up when the kernel is 4.4.262

[Joe Korty]

The following lines in kexec/kernel_version.c cause a crash dump to fail,
when the kernel is 4.4.262, or indeed any kernel whose patchlevel is >255.

	if (major >= 256 || minor >= 256 || patch >= 256) {
		fprintf(stderr, "Unsupported utsname.release: %s\n",
			utsname.release);
		return -1;
	}

	return KERNEL_VERSION(major, minor, patch);

Regards,
Joe