Fix refcounting problem which causes a segfault for following test code;

--------------------------------------------------------
#include <python2.5/Python.h>

int main(void)
{
    int i;
    for (i = 0; i < 1000; ++i)
    {
        Py_Initialize();
        PyRun_SimpleString("import pwd\n");
        Py_Finalize();
    }
    return 0;
}
--------------------------------------------------------

Reported-by: Onur Küçük <onur@pardus.org.tr>
Signed-off-by: S.Çağlar Onur <caglar@pardus.org.tr>

--- Modules/pwdmodule.c	2006-04-16 21:55:50.000000000 +0300
+++ Modules/pwdmodule.c	2009-09-08 21:44:53.000000000 +0300
@@ -193,6 +193,7 @@
 	Py_INCREF((PyObject *) &StructPwdType);
 	PyModule_AddObject(m, "struct_passwd", (PyObject *) &StructPwdType);
 	/* And for b/w compatibility (this was defined by mistake): */
+	Py_INCREF((PyObject *) &StructPwdType);
 	PyModule_AddObject(m, "struct_pwent", (PyObject *) &StructPwdType);
 	initialized = 1;
 }