scripts: Remove unused POSIX module usage

In addition to avoiding imports from unneeded modules, this fixes
a perl warning due to redefinition of getcwd() exported by both
the POSIX and Cwd modules, affecting any program executed with
«perl -w» and including the Dpkg::Source::Archive module.

Closes: #700978

Reported-by: Niels Thykier <niels@thykier.net>
Analysis-by: Raphaël Hertzog <hertzog@debian.org>

debian/changelog

@@ -12,6 +12,8 @@ dpkg (1.16.10) UNRELEASED; urgency=low
   * Do not accept Armor Header Lines inside a paragraph.
   * Do not abort dselect when multiarch is detected, as that only makes
     users downgrade and hold on an older version w/ worse multiarch support.
+  * Fix warning in Dpkg::Source::Archive with «perl -w» due to redefinition
+    of getcwd() by removing unused POSIX modules usage. Closes: #700978
 
   [ Updated programs translations ]
   * Esperanto (Felipe Castro).

scripts/Dpkg/Source/Archive.pm

@@ -25,7 +25,6 @@ use Dpkg::Gettext;
 use Dpkg::IPC;
 use Dpkg::ErrorHandling;
 
-use POSIX;
 use File::Temp qw(tempdir);
 use File::Basename qw(basename);
 use File::Spec;

scripts/changelog/debian.pl

@@ -23,7 +23,6 @@ use strict;
 use warnings;
 
 use Getopt::Long qw(:config posix_default bundling no_ignorecase);
-use POSIX;
 
 use Dpkg;
 use Dpkg::Gettext;

scripts/dpkg-genchanges.pl

@@ -23,7 +23,6 @@ use strict;
 use warnings;
 
 use Encode;
-use POSIX;
 use POSIX qw(:errno_h :signal_h);
 use Dpkg;
 use Dpkg::Gettext;