Remove useless if condition

This is useless because these fields are not set anywhere before, so
we can assign them unconditionally.  This also makes this more
consistent with ATExecAddColumn().

Reviewed-by: Alvaro Herrera <alvherre@alvh.no-ip.org>
Discussion: https://www.postgresql.org/message-id/flat/52a125e4-ff9a-95f5-9f61-b87cf447e4da@eisentraut.org

src/backend/commands/tablecmds.c

@@ -942,11 +942,8 @@ DefineRelation(CreateStmt *stmt, char relkind, Oid ownerId,
 			attr->atthasdef = true;
 		}
 
-		if (colDef->identity)
-			attr->attidentity = colDef->identity;
-
-		if (colDef->generated)
-			attr->attgenerated = colDef->generated;
+		attr->attidentity = colDef->identity;
+		attr->attgenerated = colDef->generated;
 
 		if (colDef->compression)
 			attr->attcompression = GetAttributeCompression(attr->atttypid,