Revert "Compilation warning fix for byte-run.el"

* lisp/emacs-lisp/byte-run.el (macro-declaration-function):
Revert change that causes a bootstrap failure.

; Ref eg https://hydra.nixos.org/build/94678649
1 job for master in 9 seconds
Status Job ID Name Coverage
  Test
failed #2136
test-all

00:00:09

 
Name Stage Failure
failed
test-all Test There has been a runner system failure, please try again
Running with gitlab-runner 11.6.0 (f100a208)
on gitlab-runner-docker cff9d373
Using Docker executor with image debian:stretch ...
Pulling docker image debian:stretch ...
Using docker image sha256:e1de74e67cc70422153600785c4ce4c29843a0e59e18b634c52ca133c564437f for debian:stretch ...
ERROR: Job failed (system failure): Error response from daemon: failed to start shim: exec: "docker-containerd-shim": executable file not found in $PATH: unknown (executor_docker.go:1018:1s)