fix indentation of comment

Include/frameobject.h

@@ -28,13 +28,13 @@ typedef struct _frame {
     PyObject **f_stacktop;
     PyObject *f_trace;          /* Trace function */
 
-        /* In a generator, we need to be able to swap between the exception
-           state inside the generator and the exception state of the calling
-           frame (which shouldn't be impacted when the generator "yields"
-           from an except handler).
-           These three fields exist exactly for that, and are unused for
-           non-generator frames. See the save_exc_state and swap_exc_state
-           functions in ceval.c for details of their use. */
+    /* In a generator, we need to be able to swap between the exception
+       state inside the generator and the exception state of the calling
+       frame (which shouldn't be impacted when the generator "yields"
+       from an except handler).
+       These three fields exist exactly for that, and are unused for
+       non-generator frames. See the save_exc_state and swap_exc_state
+       functions in ceval.c for details of their use. */
     PyObject *f_exc_type, *f_exc_value, *f_exc_traceback;
     /* Borrowed reference to a generator, or NULL */
     PyObject *f_gen;