Another attempt to void compiler warnings on macOS (bug#55595)

* configure.ac (WERROR_CFLAGS): Use "-Wno-unknown-pragmas" with
Clang.
1 job for master in 35 minutes and 40 seconds (queued for 2 seconds)
Status Job ID Name Coverage
  Build Images
failed #46769
build-image-inotify

00:35:40

 
Name Stage Failure
failed
build-image-inotify Build Images
 > [emacs-inotify 5/5] RUN make bootstrap:
------
executor failed running [/bin/sh -c make bootstrap]: exit code: 2
Running after script...
$ test -n "$(docker ps -aq -f name=${test_name})" && docker cp ${test_name}:checkout/test ${test_name}
$ test -n "$(docker ps -aq -f name=${test_name})" && docker rm ${test_name}
$ find ${test_name} ! \( -name "*.log" -o -name ${EMACS_TEST_JUNIT_REPORT} \) -type f -delete
find: build-image-inotify-3287d4e3: No such file or directory
ERROR: Job failed: exit code 1