Tweak recent additions in tabify-tests.el

* test/lisp/tabify-tests.el (tabify-tests--test-changes): Rename
third argument to avoid "lexical argument shadows dynamic variable"
warnings.  Use mapconcat in place of mapcar+concat.
(tabify-tests-untabify, tabify-tests-tabify): Quote function symbols
as such.
1 job for master in 52 minutes and 28 seconds (queued for 3 seconds)
Status Job ID Name Coverage
  Test
failed #1912
test-all

00:52:28

 
Name Stage Failure
failed
test-all Test
Makefile:318: recipe for target 'check-doit' failed
make[2]: *** [check-doit] Error 1
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