FindGLUT: Use link directories for libs from pkg-config
Since commit f90d1545 (FindGLUT: Use pkg-config to find flags if
available, 2021-06-11, v3.22.0-rc1~469^2), the `GLUT_LIBRARIES` may come
from `pkg-config`, in which case they may be `-l` flags instead of
absolute paths. Propagate `GLUT_LIBRARY_DIRS` to GLUT::GLUT too.
48 jobs for !6985 with fix23229 in 29 minutes and 13 seconds
(queued for 2 seconds)