Apply the big hammer:

Apply the big hammer:
o remove all of compat except for pwcache and strstuftoll; these might
  end up in libutil or similar so keep them in the subdir
o mv getid.c up to the top level; this looks like something that'll be
  makefs-specific
o eliminate private versions of .h files in sys; use system files instead
o eliminate private ffs_tables.c; use the system version directly (might
  want to adopt const'ification at some point but that's the only diff I
  can see)
o mv remaining code from sys to ffs and strip out unused bits; this now
  becomes part of makefs
o add compat defs and shims to makefs.h
o strip all vestiges of nbtool_config.h, compat_defs.h, etc.
o fixup includes after file shuffling
o rename system #defines that do implicit byte swapping to have an _swap
  suffix; e.g. DIRSIZ -> DIRSIZ_SWAP, cg_inosused -> cg_inosused_swap; if
  we ever add endian-agnostic support to the kernel these can go back to
  their original names
o strip some netbsd'isms that aren't worth shim'ing (e.g. _DIAGASSERT)

Code compiles w/o complaints but is untested.