Description of problem:
Memory leak on libvirt_virNodeGetMemoryStats API.

Version-Release number of selected component (if applicable):
libvirt-python-0.9.9-0rc1.el6.x86_64.rpm

How reproducible:
always

Steps to Reproduce:
1. Paste the following codes into test.py:

import libvirt
con = libvirt.open(None)
dom = con.lookupByName('foo')
con.getMemoryStats(0, 0)

2. valgrind -v --leak-check=full python test.py
  
Actual results:

==18633== 80 bytes in 2 blocks are definitely lost in loss record 1,281 of 2,083
==18633==    at 0x4A05FDE: malloc (vg_replace_malloc.c:236)
==18633==    by 0x39E1A85EC3: PyObject_Malloc (obmalloc.c:935)
==18633==    by 0x39E1A77831: _PyLong_New (longobject.c:75)
==18633==    by 0x39E1A79E2E: PyLong_FromUnsignedLongLong (longobject.c:892)
==18633==    by 0xB8FC0C4: libvirt_virNodeGetMemoryStats (libvirt-override.c:2372)
==18633==    by 0x39E1ADE7F3: PyEval_EvalFrameEx (ceval.c:3794)
==18633==    by 0x39E1ADF99E: PyEval_EvalFrameEx (ceval.c:3880)
==18633==    by 0x39E1AE0466: PyEval_EvalCodeEx (ceval.c:3044)
==18633==    by 0x39E1AE0541: PyEval_EvalCode (ceval.c:545)
==18633==    by 0x39E1AFB88B: run_mod (pythonrun.c:1351)
==18633==    by 0x39E1AFB95F: PyRun_FileExFlags (pythonrun.c:1337)
==18633==    by 0x39E1AFCE4B: PyRun_SimpleFileExFlags (pythonrun.c:941)
==18633==
==18633== 89 bytes in 2 blocks are definitely lost in loss record 1,398 of 2,083
==18633==    at 0x4A05FDE: malloc (vg_replace_malloc.c:236)
==18633==    by 0x39E1A85EC3: PyObject_Malloc (obmalloc.c:935)
==18633==    by 0x39E1A9053C: PyString_FromString (stringobject.c:138)
==18633==    by 0xB8FC0D3: libvirt_virNodeGetMemoryStats (libvirt-override.c:2372)
==18633==    by 0x39E1ADE7F3: PyEval_EvalFrameEx (ceval.c:3794)
==18633==    by 0x39E1ADF99E: PyEval_EvalFrameEx (ceval.c:3880)
==18633==    by 0x39E1AE0466: PyEval_EvalCodeEx (ceval.c:3044)
==18633==    by 0x39E1AE0541: PyEval_EvalCode (ceval.c:545)
==18633==    by 0x39E1AFB88B: run_mod (pythonrun.c:1351)
==18633==    by 0x39E1AFB95F: PyRun_FileExFlags (pythonrun.c:1337)
==18633==    by 0x39E1AFCE4B: PyRun_SimpleFileExFlags (pythonrun.c:941)
==18633==    by 0x39E1B094CE: Py_Main (main.c:577)

Expected results:
Fix memory leaks.

Additional info: