Avoid compilation warning in byte-run

* lisp/emacs-lisp/byte-run.el (macro-declaration-function): Avoid
compilation warning by not using `symbol-function'.
1 job for master in 53 minutes and 13 seconds (queued for 2 seconds)
Status Job ID Name Coverage
  Test
failed #2168
test-all

00:53:13

 
Name Stage Failure
failed
test-all Test
make[2]: *** [check-doit] Error 1
Makefile:318: recipe for target 'check-doit' failed
make[2]: Leaving directory '/builds/emacs/emacs/test'
Makefile:293: recipe for target 'check-expensive' failed
make[1]: *** [check-expensive] Error 2
make[1]: Leaving directory '/builds/emacs/emacs/test'
Makefile:957: recipe for target 'check-expensive' failed
make: *** [check-expensive] Error 2
ERROR: Job failed: exit code 1