package/.mk files: remove --localstatedir=/var from autotools packages

Remove --localstatedir=/var from all autotools packages where it is no longer
needed.

Also remove --localstatedir=/var/lib/dhcp from package dhcp. localstatedir is
used by dhcp to set the default directory for the leases files. This can also
be done by setting --with-*-lease-file=/var/lib/dhcp/*, which is done in
dhcp.mk.

A custom --localstatedir is left in:
* proftpd.mk
* mysql.mk

This is safe to do:
One of the good thing with autoconf is that if you pass:
        --localstatedir=/var ... --localstatedir=/var/something
Then /var/something will be used. So, we can set --localstatedir=/var
by default in the infrastructure, and still have certain packages doing
weird things override it. [Thanks to Thomas Petazzoni]

Signed-off-by: Jörg Krause <jkrause@posteo.de>
Reviewed-by: Arnout Vandecappelle (Essensium/Mind) <arnout@mind.be>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>