Refactor With.a.zErr into With.a.zCteErr.  No logic changes.

FossilOrigin-Name: 58ba73630ecc4bc58b03a7962dd45b305ef605ef
diff --git a/src/sqliteInt.h b/src/sqliteInt.h
index a57f00a..867a608 100644
--- a/src/sqliteInt.h
+++ b/src/sqliteInt.h
@@ -3030,7 +3030,7 @@
     char *zName;                    /* Name of this CTE */
     ExprList *pCols;                /* List of explicit column names, or NULL */
     Select *pSelect;                /* The definition of this CTE */
-    const char *zErr;               /* Error message for circular references */
+    const char *zCteErr;            /* Error message for circular references */
   } a[1];
 };