syscall tables.
If necessary, pull in <bsd.sys.mk> to get the definition of HOST_SH; Makefiles that pull in one of (most of) <bsd.*.mk> will get this anyway.
This gets most existing m68k a.out binaries working with m68k ELF kernels. There are still some remaining ABI issues to track down; most notably, some ioctl(2) calls are affected by the change.