gnucash stable: add extern "C" wrapper to header files

[Christopher Lam]

Updated	 via  https://github.com/Gnucash/gnucash/commit/75456bbb (commit)
	from  https://github.com/Gnucash/gnucash/commit/77cb9c6a (commit)



commit 75456bbb298cd76f0e0889ad96975aeb3a2fa5bc
Author: Christopher Lam <christopher.lck at gmail.com>
Date:   Mon Mar 27 14:18:02 2023 +0800

    add extern "C" wrapper to header files
    
    to be usable from cpp



Summary of changes:
 gnucash/gnome-utils/dialog-account.h | 8 ++++++++
 gnucash/gnome/window-reconcile.h     | 8 ++++++++
 2 files changed, 16 insertions(+)