Don't leak .png files into tmp

Temp directory created by copy_images (which contains copies of .png files
from any given icon-themes folder) was left behind. Happening at least since
commit 4e3dc8c1

Date:   Fri Jun 3 17:09:14 2016 +0200

    remove use of Archive::Zip

With packimages.pl now used to package also screenshot images (in
multiple languages), tmp fills up quickly. This is fatal on Windows

Change-Id: Ie35c33277a80ed9085815f30b846bb97a365afb1
Reviewed-on: https://gerrit.libreoffice.org/31947Reviewed-by: Katarina Behrens <Katarina.Behrens@cib.de>
Tested-by: Katarina Behrens <Katarina.Behrens@cib.de>

solenv/bin/packimages.pl

@@ -28,7 +28,7 @@ use Getopt::Long;
 use File::Find;
 use File::Basename;
 use File::Copy qw(copy);
-use File::Path qw(make_path);
+use File::Path qw(make_path rmtree);
 require File::Temp;
 use File::Temp qw(tempdir);
 
@@ -99,6 +99,9 @@ if ( $do_rebuild == 1 ) {
     create_zip_archive($zip_hash_ref, \%links, $tmpdir);
     replace_file($tmp_out_file, $out_file);
     print_message("packing  $out_file finished.") if $verbose;
+
+    rmtree($tmpdir);
+    print_error("failed to delete $tmpdir") if -e $tmpdir;
 } else {
     print_message("$out_file up to date. nothing to do.") if $verbose;
 }