Snippets for emacs 31.1 from Nix aarch64-linux

Sourced from https://hydra.nixos.org/log/241bvrnlslm7y1j56plhl740m6f152q9-emacs-nox-31.1.drv.

• ../lib/alloca.h:47:18: warning: argument to 'alloca' is too large [-Walloca-larger-than=]
     47 | #  define alloca __builtin_alloca