MFC: r246106, r246139

Mark tftp_log() as __printflike() and deal with the fallout.
MFC: r235857

mdoc: Only use macros inside a reference block.
MFC: r246257

Improve r238673 (MFC'ed to stable/9 in r239494) to additionally allow
for odd-aligned buffers as passed in by smartd of smartmontools.
While at it, hint the compiler that 32-bit PIO is the most likely
case (idea from Linux) and use bus_{read,write}_stream_2(9) instead
of bus_{read,write}_multi_stream_2(9) for single count reads/writes.
MFC: r246300

- Make pci_ns8250_ids[] const.
- Use DEVMETHOD_END.
- Use NULL instead of 0 for pointers.
MFC: r246689, r246696

Make SYSCTL_{LONG,QUAD,ULONG,UQUAD}(9) work as advertised and also handle
constant values.

Reviewed by:	kib
MFC: r242854 (by rdivacky)

Initialize hdrlen to 0 to avoid clang warning in NOINET case.

This fixes the kernel build for INET6 only kernels.

Approved by:	cognet