Dpkg::Dist::Files: Do not try to load non-files in load_dir method

Non-Linux systems allow to open directories, which return their
contents, this makes the load method fail with parsing errors. Make
the code only try to ever load regular files.

debian/changelog

@@ -1,6 +1,8 @@
 dpkg (1.18.13) UNRELEASED; urgency=medium
 
-  *
+  * Perl modules:
+    - Do not try to load non-files in Dpkg::Dist::Files load_dir method.
+      Fixes test failures on non-Linux architectures.
 
  -- Guillem Jover <guillem@debian.org>  Sun, 06 Nov 2016 06:28:11 +0100
 

scripts/Dpkg/Dist/Files.pm

@@ -110,7 +110,9 @@ sub load_dir {
     my $dh = IO::Dir->new($dir) or syserr(g_('cannot open directory %s'), $dir);
 
     while (defined(my $file = $dh->read)) {
-        $count += $self->load("$dir/$file");
+        my $pathname = "$dir/$file";
+        next unless -f $pathname;
+        $count += $self->load($pathname);
     }
 
     return $count;