dselect-multicd: replace/drop obsolete dpkg commands

dpkg --print-installation-architecture is deprecated in favor
of dpkg --print-architecture. dpkg --forget-old-unavail is obsolete.

dselect/methods/multicd/install

@@ -29,7 +29,7 @@ cd "$vardir/methods/$method"
 
 #debug() { echo "DEBUG: $@"; }
 debug() { true; }
-iarch=`dpkg --print-installation-architecture`
+iarch=`dpkg --print-architecture`
 ismulti() { test -e "$1/.disk/info" || test -e "$1$2/.disk/info"; }
 
 # 1/ mountpoint

dselect/methods/multicd/setup

@@ -32,7 +32,7 @@ test -d "$vardir/methods/$method" || mkdir "$vardir/methods/$method"
 cd "$vardir/methods/$method"
 tp=/tmp/ddm$$
 
-iarch=`dpkg --print-installation-architecture`
+iarch=`dpkg --print-architecture`
 dist=stable
 
 xit=1

dselect/methods/multicd/update

@@ -20,7 +20,7 @@ set -e
 vardir="$1"
 method=$2
 option=$3
-iarch=`dpkg --print-installation-architecture`
+iarch=`dpkg --print-architecture`
 
 cd "$vardir/methods/$method"
 
@@ -124,8 +124,6 @@ done
 
 cp -f $vardir/available $vardir/methods/$method
 
-dpkg --forget-old-unavail
-
 echo -n 'Update OK.  Hit RETURN.  '
 read response