Remove absolete function TupleDescGetSlot().

TupleDescGetSlot() was kept around for backward compatibility for
user-written SRFs. With the TupleTableSlot abstraction work, that code
will need to be version specific anyway, so there's no point in
keeping the function around any longer.

Author: Ashutosh Bapat
Reviewed-By: Andres Freund
Discussion: https://postgr.es/m/20180220224318.gw4oe5jadhpmcdnm@alap3.anarazel.de

src/backend/executor/execTuples.c

@@ -1125,28 +1125,6 @@ BlessTupleDesc(TupleDesc tupdesc)
 	return tupdesc;				/* just for notational convenience */
 }
 
-/*
- * TupleDescGetSlot - Initialize a slot based on the supplied tupledesc
- *
- * Note: this is obsolete; it is sufficient to call BlessTupleDesc on
- * the tupdesc.  We keep it around just for backwards compatibility with
- * existing user-written SRFs.
- */
-TupleTableSlot *
-TupleDescGetSlot(TupleDesc tupdesc)
-{
-	TupleTableSlot *slot;
-
-	/* The useful work is here */
-	BlessTupleDesc(tupdesc);
-
-	/* Make a standalone slot */
-	slot = MakeSingleTupleTableSlot(tupdesc);
-
-	/* Return the slot */
-	return slot;
-}
-
 /*
  * TupleDescGetAttInMetadata - Build an AttInMetadata structure based on the
  * supplied TupleDesc. AttInMetadata can be used in conjunction with C strings