Add imenu support to xref

* lisp/progmodes/xref.el (xref--imenu-prev-index-position)
(xref--imenu-extract-index-name): Add functions to get imenu support.
(xref--xref-buffer-mode): Set imenu variables to the new functions.
* etc/NEWS: Add corresponding entry (bug#36974).
1 job for master in 90 minutes and 1 second (queued for 6 seconds)
Status Job ID Name Coverage
failed #3091


Name Stage Failure
test-all Test The script exceeded the maximum execution time set for the job
make -C test check-expensive
make[1]: Entering directory '/builds/emacs/emacs/test'
rm -f ./*.tmp
make[2]: Entering directory '/builds/emacs/emacs/test'
make[3]: Entering directory '/builds/emacs/emacs/test'
ELC lisp/net/tramp-tests.elc
GEN lisp/net/tramp-tests.log
Pulling docker image gitlab/gitlab-runner-helper:x86_64-d0b76032 ...
ERROR: Job failed: execution took longer than 1h30m0s seconds