Only print the rtl::Reference's pointer

...but do not pretty-print its dereferenced value.  This is in line with the
handling of css::uno::Reference, and avoids gdb Python exceptions when trying to
print uninitialized rtl::Reference instances (which can e.g. happen during a
"backtrace full").

Change-Id: I9a3c0a6441cf23cba748183226832d2ba23bd531

solenv/gdb/libreoffice/sal.py

@@ -68,8 +68,7 @@ class RtlReferencePrinter(object):
     def to_string(self):
         pointee = self.val['m_pBody']
         if pointee:
-            val = pointee.dereference()
-            return '%s to %s' % (self.typename, str(val))
+            return '%s to %s' % (self.typename, str(pointee))
         else:
             return "empty %s" % self.typename