Add some obvious branch hints.

Cython/Utility/CythonFunction.c

@@ -725,7 +725,7 @@ static PyTypeObject __pyx_CyFunctionType_type = {
 
 static int __pyx_CyFunction_init(void) {
     __pyx_CyFunctionType = __Pyx_FetchCommonType(&__pyx_CyFunctionType_type);
-    if (__pyx_CyFunctionType == NULL) {
+    if (unlikely(__pyx_CyFunctionType == NULL)) {
         return -1;
     }
     return 0;
@@ -735,7 +735,7 @@ static CYTHON_INLINE void *__Pyx_CyFunction_InitDefaults(PyObject *func, size_t
     __pyx_CyFunctionObject *m = (__pyx_CyFunctionObject *) func;
 
     m->defaults = PyObject_Malloc(size);
-    if (!m->defaults)
+    if (unlikely(!m->defaults))
         return PyErr_NoMemory();
     memset(m->defaults, 0, size);
     m->defaults_pyobjects = pyobjects;