[libxml++] Schema::get_name(): Don't use null pointer

[Kjell Ahlstedt <kjellahl src gnome org>]

commit 65fe95a374652e9156bff99a02a3fe8b035e0b3f
Author: Kjell Ahlstedt <kjell ahlstedt bredband net>
Date:   Sat Oct 11 11:43:50 2014 +0200

    Schema::get_name(): Don't use null pointer
    
    * libxml++/schema.cc: Don't use null pointers in get_name(),
    get_target_namespace() and get_version().

 libxml++/schema.cc |    6 +++---
 1 files changed, 3 insertions(+), 3 deletions(-)
---
diff --git a/libxml++/schema.cc b/libxml++/schema.cc
index d33906a..a1e6351 100644
--- a/libxml++/schema.cc
+++ b/libxml++/schema.cc
@@ -69,17 +69,17 @@ void Schema::set_document(Document* document, bool embed)
 
 Glib::ustring Schema::get_name() const
 {
-  return impl_ ? (char*)impl_->name : "";
+  return (impl_ && impl_->name) ? (char*)impl_->name : "";
 }
 
 Glib::ustring Schema::get_target_namespace() const
 {
-  return impl_ ? (char*)impl_->targetNamespace : "";
+  return (impl_ && impl_->targetNamespace) ? (char*)impl_->targetNamespace : "";
 }
 
 Glib::ustring Schema::get_version() const
 {
-  return impl_ ? (char*)impl_->version : "";
+  return (impl_ && impl_->version) ? (char*)impl_->version : "";
 }
 
 void Schema::release_underlying()