bug#40337: 28.0.50; Enable case-fold-search in hi-lock

[Paul Eggert]

> So I pushed everything to master.

This change causes the hi-lock-bug26666 test to fail on my Fedora 31 x86-64 
host. (cd test && make lisp/hi-lock-tests) outputs:

make[1]: Entering directory '/home/eggert/src/gnu/emacs/static-checking/test'
  GEN      lisp/hi-lock-tests.log
Running 2 tests (2020-04-11 20:16:12-0700, selector `(not (tag :unstable))')
Test hi-lock-bug26666 backtrace:
  signal(ert-test-failed (((should (equal hi-lock--unused-faces (cdr f
  ert-fail(((should (equal hi-lock--unused-faces (cdr faces))) :form (
  (if (unwind-protect (setq value-2 (apply fn-0 args-1)) (setq form-de
  (let (form-description-4) (if (unwind-protect (setq value-2 (apply f
  (let ((value-2 'ert-form-evaluation-aborted-3)) (let (form-descripti
  (let* ((fn-0 #'equal) (args-1 (condition-case err (let ((signal-hook
  (progn (insert "a A b B\n") (let* ((vnew #'(lambda (_prompt _coll _x
  (unwind-protect (progn (insert "a A b B\n") (let* ((vnew #'(lambda (
  (save-current-buffer (set-buffer temp-buffer) (unwind-protect (progn
  (let ((temp-buffer (generate-new-buffer " *temp*"))) (save-current-b
  (let ((faces hi-lock-face-defaults)) (let ((temp-buffer (generate-ne
  (closure (t) nil (let ((faces hi-lock-face-defaults)) (let ((temp-bu
  ert--run-test-internal(#s(ert--test-execution-info :test #s(ert-test
  ert-run-test(#s(ert-test :name hi-lock-bug26666 :documentation "Test
  ert-run-or-rerun-test(#s(ert--stats :selector (not (tag :unstable))
  ert-run-tests((not (tag :unstable)) #f(compiled-function (event-type
  ert-run-tests-batch((not (tag :unstable)))
  ert-run-tests-batch-and-exit((not (tag :unstable)))
  eval((ert-run-tests-batch-and-exit '(not (tag :unstable))) t)
  command-line-1(("-L" ":." "-l" "ert" "-l" "lisp/hi-lock-tests.el" "-
  command-line()
  normal-top-level()
Test hi-lock-bug26666 condition:
    (ert-test-failed
     ((should
       (equal hi-lock--unused-faces
              (cdr faces)))
      :form
      (equal
       ("hi-green" "hi-blue" "hi-salmon" "hi-aquamarine" "hi-black-b" 
"hi-blue-b" "hi-red-b" "hi-green-b" "hi-black-hb")
       ("hi-pink" "hi-green" "hi-blue" "hi-salmon" "hi-aquamarine" "hi-black-b" 
"hi-blue-b" "hi-red-b" "hi-green-b" "hi-black-hb"))
      :value nil :explanation
      (proper-lists-of-different-length 9 10
					("hi-green" "hi-blue" "hi-salmon" "hi-aquamarine" "hi-black-b" "hi-blue-b" 
"hi-red-b" "hi-green-b" "hi-black-hb")
					("hi-pink" "hi-green" "hi-blue" "hi-salmon" "hi-aquamarine" "hi-black-b" 
"hi-blue-b" "hi-red-b" "hi-green-b" "hi-black-hb")
                                        first-mismatch-at 0)))
   FAILED  1/2  hi-lock-bug26666 (0.000209 sec)
   passed  2/2  hi-lock-test-set-pattern (0.000104 sec)

Ran 2 tests, 1 results as expected, 1 unexpected (2020-04-11 20:16:13-0700, 
0.102481 sec)

1 unexpected results:
   FAILED  hi-lock-bug26666

Makefile:182: recipe for target 'lisp/hi-lock-tests.log' failed
make[1]: *** [lisp/hi-lock-tests.log] Error 1
make[1]: Leaving directory '/home/eggert/src/gnu/emacs/static-checking/test'
Makefile:248: recipe for target 'lisp/hi-lock-tests' failed
make: *** [lisp/hi-lock-tests] Error 2