Eliminate the need for the Column.zDflt (using Column.pDflt instead) to reduce

the amount of memory needed to hold the schema.

FossilOrigin-Name: d8c94a46dfa94930732c2de2aa79675c5087d36e

src/sqliteInt.h

@@ -1545,7 +1545,6 @@ struct Module {
 struct Column {
   char *zName;     /* Name of this column */
   Expr *pDflt;     /* Default value of this column */
-  char *zDflt;     /* Original text of the default value */
   char *zType;     /* Data type for this column */
   char *zColl;     /* Collating sequence.  If NULL, use the default */
   u8 notNull;      /* An OE_ code for handling a NOT NULL constraint */