Check for NULL return value from new_CArgObject calls.

Modules/_ctypes/_ctypes.c

@@ -1282,6 +1282,8 @@ c_void_p_from_param(PyObject *type, PyObject *value)
 		struct fielddesc *fd = getentry("z");
 
 		parg = new_CArgObject();
+		if (parg == NULL)
+			return NULL;
 		parg->pffi_type = &ffi_type_pointer;
 		parg->tag = 'z';
 		parg->obj = fd->setfunc(&parg->value, value, 0);
@@ -1297,6 +1299,8 @@ c_void_p_from_param(PyObject *type, PyObject *value)
 		struct fielddesc *fd = getentry("Z");
 
 		parg = new_CArgObject();
+		if (parg == NULL)
+			return NULL;
 		parg->pffi_type = &ffi_type_pointer;
 		parg->tag = 'Z';
 		parg->obj = fd->setfunc(&parg->value, value, 0);
@@ -1333,6 +1337,8 @@ c_void_p_from_param(PyObject *type, PyObject *value)
 		CFuncPtrObject *func;
 		func = (CFuncPtrObject *)value;
 		parg = new_CArgObject();
+		if (parg == NULL)
+			return NULL;
 		parg->pffi_type = &ffi_type_pointer;
 		parg->tag = 'P';
 		Py_INCREF(value);