gnucash stable: [Account.hpp] use std::optional for cached values

[Christopher Lam]

Updated	 via  https://github.com/Gnucash/gnucash/commit/2251bf89 (commit)
	from  https://github.com/Gnucash/gnucash/commit/01bffa48 (commit)



commit 2251bf8966ec1cc92e9eed22cc2110990593bc41
Author: Christopher Lam <christopher.lck at gmail.com>
Date:   Sat Apr 13 20:56:21 2024 +0800

    [Account.hpp] use std::optional for cached values
    
    whereby {} denotes uncached values



Summary of changes:
 libgnucash/engine/Account.cpp  | 40 +++++++++++++++-------------------------
 libgnucash/engine/AccountP.hpp | 17 +++++------------
 2 files changed, 20 insertions(+), 37 deletions(-)