Fix refcount leak in error cases.  Bug found by coverity.
diff --git a/Modules/_ctypes/cfield.c b/Modules/_ctypes/cfield.c
index ef85b87..96264e7 100644
--- a/Modules/_ctypes/cfield.c
+++ b/Modules/_ctypes/cfield.c
@@ -1452,11 +1452,14 @@
 		size += 1; /* terminating NUL */
 		size *= sizeof(wchar_t);
 		buffer = (wchar_t *)PyMem_Malloc(size);
-		if (!buffer)
+		if (!buffer) {
+			Py_DECREF(value);
 			return PyErr_NoMemory();
+		}
 		memset(buffer, 0, size);
 		keep = PyCObject_FromVoidPtr(buffer, PyMem_Free);
 		if (!keep) {
+			Py_DECREF(value);
 			PyMem_Free(buffer);
 			return NULL;
 		}