Renamed --libstatedir to --statedir.

In BSD systems, it's usually </var/db> or some other dir under </var>
that is not </var/lib>, so $statedir is a more generic name.  See
hier(7).

Reported-by: Andrei Zeliankou <zelenkov@nginx.com>
Reported-by: Zhidao Hong <z.hong@f5.com>
Reviewed-by: Konstantin Pavlov <thresh@nginx.com>
Reviewed-by: Andrew Clayton <a.clayton@nginx.com>
Cc: Liam Crilly <liam@nginx.com>
Signed-off-by: Alejandro Colomar <alx@nginx.com>

pkg/deb/Makefile

@@ -117,7 +117,7 @@ endif
 
 CONFIGURE_ARGS_COMMON=\
 	--prefix=/usr \
-	--libstatedir=/var/lib/unit \
+	--statedir=/var/lib/unit \
 	--control="unix:/var/run/control.unit.sock" \
 	--pid=/var/run/unit.pid \
 	--log=/var/log/unit.log \