gnucash stable: Apply -Wall -Werr -Wmissing-prototypes to C++ compilation on Windows.

[John Ralls]

Updated	 via  https://github.com/Gnucash/gnucash/commit/d42e2c5e (commit)
	from  https://github.com/Gnucash/gnucash/commit/4c159fa5 (commit)



commit d42e2c5e40216f4a587e1efaef618229174087d2
Author: John Ralls <jralls at ceridwen.us>
Date:   Sun Mar 29 13:46:27 2026 -0700

    Apply -Wall -Werr -Wmissing-prototypes to C++ compilation on Windows.
    
    And fix the resulting errors.



Summary of changes:
 CMakeLists.txt                                | 2 +-
 gnucash/gnome/assistant-loan.cpp              | 3 +++
 libgnucash/core-utils/gnc-filepath-utils.cpp  | 3 +--
 libgnucash/engine/gnc-datetime.cpp            | 4 ++--
 libgnucash/engine/gnc-timezone.cpp            | 6 +++---
 libgnucash/engine/test/gtest-gnc-datetime.cpp | 4 ++--
 6 files changed, 12 insertions(+), 10 deletions(-)