More compiler warning fixes

[n-t-roff]

Just being curious--why did you rename d to e?

In case of an unused parameter I write (void)parameter; into the function instead of using __unused. Isn't using (void) a more general approach (meaning being more C standard instead of a special compiler feature)?

(There is no issue in applying the pull request, it's just a discussion.)

[bapt]

I renamed d to e just by lack of creativity, it was shadowing struct d *d; in ext.h

As for the void I have no preference, this is up to you :) I'm used to __unused in the FreeBSD source tree, hence the direction I took