Dpkg::Substvars: Add new member function set_as_used()

This sets a subtsvar and marks it as used, so no warnings are produced
even if the variable is never used.

debian/changelog

@@ -31,6 +31,7 @@ dpkg (1.16.4) UNRELEASED; urgency=low
   * Do not obscure Dpkg::Source::Package ‘require’ errors with custom
     error message. Thanks to Thomas Adam <thomas.adam@smoothwall.net> and
     Jonathan Nieder <jrnieder@gmail.com>.
+  * Add new Dpkg::Substvars::set_as_used() member function.
 
   [ Updated man page translations ]
   * German (Helge Kreutzmann).

scripts/Dpkg/Substvars.pm

@@ -18,7 +18,7 @@ package Dpkg::Substvars;
 use strict;
 use warnings;
 
-our $VERSION = "1.00";
+our $VERSION = "1.01";
 
 use Dpkg qw($version);
 use Dpkg::Arch qw(get_host_arch);
@@ -94,6 +94,19 @@ sub set {
     $self->{'vars'}{$key} = $value;
 }
 
+=item $s->set_as_used($key, $value)
+
+Add/replace a substitution and mark it as used (no warnings will be produced
+even if unused).
+
+=cut
+
+sub set_as_used {
+    my ($self, $key, $value) = @_;
+    $self->set($key, $value);
+    $self->no_warn($key);
+}
+
 =item $s->get($key)
 
 Get the value of a given substitution.