vm/rpm/rpm-closure.pl: make it deterministic

Some recent perl version introduced "keys" to return the keys
in random order. As some of the packages are solved by "provides" and
based on the order, this randomness affects what packages get into the
closure.

This problem may be in other nix perl scripts.

pkgs/build-support/vm/rpm/rpm-closure.pl

···
 }
 
 my %provides;
-PKG: foreach my $pkgName (keys %pkgs) {
+PKG: foreach my $pkgName (sort(keys %pkgs)) {
     #print STDERR "looking at $pkgName\n";
     my $pkg = $pkgs{$pkgName};