Remove the printf builtin command from sh(1), which command is not

Remove the printf builtin command from sh(1), which command is not
used so often that it's worth keeping it as a builtin.

Now that all the printf invocations from within the system startup
scripts, we can safely remove it.

Urged by:	sheldonh  :)

No MFC is planned so far because it may break compatibility and
violate POLA.