Snippets for 2bwm 0.3 from Nix x86_64-linux

Sourced from https://hydra.nixos.org/log/045vs2x3jgsdy0w536sx9y9sggi432my-2bwm-0.3.drv.

• 2bwm.c:3257:9: warning: argument 2 null where non-null expected [-Wnonnull]
   3257 |         execvp(TWOBWM_PATH, NULL);
        |         ^~~~~~