CLSA-2026-1780061802 Fix CVE(s): CVE-2026-42050

SECURITY UPDATE: fix stack-based buffer overflow in XTileImage triggered by a malicious MIFF file when right-clicking a tile to invoke the Load / Update menu item - debian/patches/CVE-2026-42050.patch: fix stack-based buffer overflow in XTileImage triggered by a malicious MIFF file when...