DragonFly now uses dynamic binaries in the root filesystem

[Francois Tigeot]

Having /bin and /sbin binaries be dynamic is a requirement to use
some modern authentication technologies like NSS and PAM.

This is now the case on DragonFly 3.7 (-master); I have pushed some
commits during the last weekend to introduce the required infrastructure
and finally switch /bin and /sbin binaries from static to dynamic ones.

These additional directories are now present in the root filesystem:

  /lib
  /libexec

/lib contains a few dynamic libraries necessary to run the programs in
/bin and /sbin and /libexec is the new location for the ELF dynamic
run-time loader.

Adding these directories to / was necessary since /usr/lib may be on a
different filesystem, not yet mounted at system startup.
(This is even the case on the majority of DragonFly installation given
it's what the installer does).

For people tracking -master, a full buildworld + installworld sequence
is required to avoid trouble.

-- 
Francois Tigeot