gdbhooks.py: fix prettyprinting of NULL vec<>*

	* gdbhooks.py (VecPrinter.children): Don't attempt to iterate
	the children of a NULL pointer.

From-SVN: r205139

gcc/ChangeLog

+2013-11-20  David Malcolm  <dmalcolm@redhat.com>
+
+	* gdbhooks.py (VecPrinter.children): Don't attempt to iterate
+	the children of a NULL pointer.
+
 2013-11-20  Robert Suchanek  <Robert.Suchanek@imgtec.com>
 
 	* lra.c (lra): Set lra_in_progress before check_rtl call.

gcc/gdbhooks.py

@@ -383,6 +383,8 @@ class VecPrinter:
         return '0x%x' % long(self.gdbval)
 
     def children (self):
+        if long(self.gdbval) == 0:
+            return
         m_vecpfx = self.gdbval['m_vecpfx']
         m_num = m_vecpfx['m_num']
         m_vecdata = self.gdbval['m_vecdata']