prelude.c is an automatically generated file by template/prelude.c.tmpl.
However it does not contain any required functions. So remove it from
dependency.
Also miniprelude.c is included by mini_builtin.c and does not need
to make miniprelude.o.
FreeBSD make works differently with `-j` option.
> -j max_jobs
> Specify the maximum number of jobs that `make` may have running
> at any one time. The value is saved in `.MAKE.JOBS.` Turns
> compatibility mode off, unless the `B` flag is also specified.
> When compatibility mode is off, all commands associated with a
> target are executed in a single shell invocation as opposed to
> the traditional one shell invocation per line. This can break
> traditional scripts which change directories on each command
> invocation and then expect to start with a fresh environment on
> the next line. It is more efficient to correct the scripts
> rather than turn backwards compatibility on.
Stop using exit, cd, exec in middle of commands.