Remove useless check for NULL subexpression.

Coverity rightly gripes that it's silly to have a test here when
the adjacent ExecEvalExpr() would choke on a NULL expression pointer.

Petr Jelinek

src/backend/access/tablesample/tablesample.c

@@ -110,12 +110,6 @@ tablesample_init(SampleScanState *scanstate, TableSampleClause *tablesample)
 		Expr	   *argexpr = (Expr *) lfirst(arg);
 		ExprState  *argstate = ExecInitExpr(argexpr, (PlanState *) scanstate);
 
-		if (argstate == NULL)
-		{
-			fcinfo.argnull[i] = true;
-			fcinfo.arg[i] = (Datum) 0;;
-		}
-
 		fcinfo.arg[i] = ExecEvalExpr(argstate, econtext,
 									 &fcinfo.argnull[i], NULL);
 		i++;