I've found two problems with the linux compat lkm.  One is easy to fix, the
other is harder and so I'll ask for comments here.

First, linux_exec.c references elf32_copyargs which is only defined in
/usr/include/sys/exec_elf.h when EXEC_ELF32 is defined.  So that needs to
be added as "-DEXEC_ELF32" to the sys/lkm/compat/linux/Makefile.  Either
that, or have the prototype visible whether EXEC_ELF32 is defined or not.

Second, linux_machdep.c fails to build because it trys to include vt.h
which is normally generated for a kernel build by /usr/sbin/config.  How
should these configured components be handled for lkm's??  Sorry if this
question has already been discussed, but since -current doesn't build, I'm
guessing that it hasn't.

Dave