Fix oversights of "support X core font driver on cairo" change

* src/Makefile.in (FONT_OBJ): Fix comment for USE_CAIRO.
* src/xfns.c (x_create_tip_frame) [USE_CAIRO]: Register xfont_driver.
1 job for master in 90 minutes (queued for 1 second)
Status Job ID Name Coverage
  Test
failed #2274
test-all

01:30:00

 
Name Stage Failure
failed
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-f100a208 ...
ERROR: Job failed: execution took longer than 1h30m0s seconds