Snippets for emacs 31.1 from Nix x86_64-linux

Sourced from https://hydra.nixos.org/log/n5wmp0bl6xx7nsfc650qwp5i2n651rvd-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