Deparser: Correctly set A_EXPR context in deparseExpr for deparseAExpr

Note that the deparseAExpr function (used for deparsing A_Expr nodes)
can be called from both a_expr and b_expr contexts, but we previously
always passed NONE as the context.

Besides now passing down the context, the function also used to add
outer parenthesis to AEXPR_OP calls. This appears unnecessary (b_expr
allows operator expressions without wrapping parenthesis) and was not
utilized in practice, so remove that to avoid extra parenthesis.

src/postgres_deparse.c

@@ -332,7 +332,7 @@ static void deparseExpr(StringInfo str, Node *node, DeparseNodeContext context)
 			deparseCollateClause(str, castNode(CollateClause, node));
 			break;
 		case T_A_Expr:
-			deparseAExpr(str, castNode(A_Expr, node), DEPARSE_NODE_CONTEXT_NONE);
+			deparseAExpr(str, castNode(A_Expr, node), DEPARSE_NODE_CONTEXT_A_EXPR);
 			break;
 		case T_BoolExpr:
 			deparseBoolExpr(str, castNode(BoolExpr, node));
@@ -3057,10 +3057,6 @@ static void deparseAExpr(StringInfo str, A_Expr* a_expr, DeparseNodeContext cont
 	switch (a_expr->kind) {
 		case AEXPR_OP: /* normal operator */
 			{
-				bool need_outer_parens = context == DEPARSE_NODE_CONTEXT_A_EXPR;
-
-				if (need_outer_parens)
-					appendStringInfoChar(str, '(');
 				if (a_expr->lexpr != NULL)
 				{
 					if (need_lexpr_parens)
@@ -3080,9 +3076,6 @@ static void deparseAExpr(StringInfo str, A_Expr* a_expr, DeparseNodeContext cont
 					if (need_rexpr_parens)
 						appendStringInfoChar(str, ')');
 				}
-
-				if (need_outer_parens)
-					appendStringInfoChar(str, ')');
 			}
 			return;
 		case AEXPR_OP_ANY: /* scalar op ANY (array) */