Mitigate byte-compile warning in arc-mode

* lisp/arc-mode.el (byte-after): Remove defsubst.
Replace all calls to byte-after with get-byte throughout the file,
because byte-after gave compilation warnings.
1 job for master in 57 minutes and 39 seconds (queued for 3 seconds)
Status Job ID Name Coverage
  Test
failed #1807
test-all

00:57:39

 
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