Bug 460911 - Make the installer complain about missing files on stdout; r=benjamin

xpinstall/packager/Packager.pm

@@ -147,7 +147,7 @@ sub Copy {
 
     # if we hit this, it's either a file in the package file that is
     # not in the src directory, or it is not a valid entry.
-    warn "Warning: package error or possible missing or unnecessary file: $line ($package, $lineno).\n";
+    print "Warning: package error or possible missing or unnecessary file: $line ($package, $lineno).\n";
 
   } # LINE