Roll our own version of abs2rel to handle MOZ_OBJDIRs with .. in their path

Bug #135589 r=kaie

build/unix/abs2rel.pl

@@ -0,0 +1,41 @@
+#!env perl
+
+# The contents of this file are subject to the Mozilla Public
+# License Version 1.1 (the "License"); you may not use this file
+# except in compliance with the License. You may obtain a copy of
+# the License at http://www.mozilla.org/MPL/
+
+# The Initial Developer of the Original Code is Netscape
+# Communications Corporation.  Portions created by Netscape are
+# Copyright (C) 2002 Netscape Communications Corporation. All
+# Rights Reserved.
+
+use File::Spec::Unix;
+use strict;
+
+print "Usage: $0 dest_path start_path\n" if ($#ARGV+1 != 2);
+my $finish = my_canonpath(shift);
+my $start = my_canonpath(shift);
+
+my $res = File::Spec::Unix->abs2rel($finish, $start);
+
+#print STDERR "abs2rel($finish,$start) = $res\n";
+print "$res\n";
+
+sub my_canonpath($) {
+    my ($file) = @_;
+    my (@inlist, @outlist, $dir);
+
+    # Do what File::Spec::Unix->no_upwards should do
+    my @inlist = split(/\//, File::Spec::Unix->canonpath($file));
+    foreach $dir (@inlist) {
+	if ($dir eq '..') {
+	    pop @outlist;
+	} else {
+	    push @outlist, $dir;
+	}
+    }
+    $file = join '/',@outlist;
+    return $file;
+}
+