Fix native Windows zip build regression from bug 192688 r=bsmedberg

config/make-jars.pl

@@ -80,9 +80,6 @@ my $jarDir = $chromeDir;
 if (defined($::opt_j)) {
     $jarDir = $::opt_j;
 }
-if ($jarDir !~ /^\//) {
-    $jarDir = getcwd() . '/' . $jarDir;
-}
 
 my $verbose = 0;
 if (defined($::opt_v)) {
@@ -218,7 +215,10 @@ sub JarIt
 {
     my ($destPath, $jarPath, $jarfile, $args, $overrides) = @_;
     my $oldDir = cwd();
-    my $jarchive = $jarPath . '/' . $jarfile . '.jar';
+    my @destPath = _moz_splitpath("$destPath/$jarfile");
+    my @jarchive = _moz_splitpath("$jarPath/$jarfile.jar");
+    shift @destPath, shift @jarchive while $destPath[0] eq $jarchive[0];
+    my $jarchive = "../" x @destPath . join("/", @jarchive);
     chdir("$destPath/$jarfile");
 
     if ("$fileformat" eq "flat" || "$fileformat" eq "symlink") {
@@ -288,6 +288,17 @@ sub JarIt
     #print "cd $oldDir\n";
 }
 
+sub _moz_splitpath
+{
+    my ($path) = @_;
+    my @dirs = split(m:/:, $path);
+    foreach (reverse 0 .. $#dirs) {
+      splice(@dirs, $_, 1) if $dirs[$_] eq ".";
+      splice(@dirs, $_, 2) if $dirs[$_] eq "..";
+    }
+    return @dirs;
+}
+
 sub _moz_rel2abs
 {
     my ($path, $keep_file) = @_;