Fix a problem causing an OOM within an ALTER TABLE ADD COLUMN command that adds a column with a CHECK constraint to go unreported.

FossilOrigin-Name: a33f5e93ecb7d84291f6fecc7b60f0c555034aa47e24584c63c78d8a94710d82

src/sqliteInt.h

@@ -3555,7 +3555,6 @@ struct Parse {
   AutoincInfo *pAinc;  /* Information about AUTOINCREMENT counters */
   Parse *pToplevel;    /* Parse structure for main program (or NULL) */
   Table *pTriggerTab;  /* Table triggers are being coded for */
-  Parse *pParentParse; /* Parent parser if this parser is nested */
   union {
     int addrCrTab;         /* Address of OP_CreateBtree on CREATE TABLE */
     Returning *pReturning; /* The RETURNING clause */