editors/emacs: Apply a security fix from upstream

Previous fix for CVE-2024-53920 was incomplete[0].

[0] https://www.openwall.com/lists/oss-security/2026/09/14/1

PR: 298557
MFH: 2026Q3
Security: 7ba6c085-1590-491a-98ce-5452646b196f
Security: CVE-2024-53920
(cherry picked from commit 93d11220ce575a5ab5fff7f1dc1e587631bf1ac9)