CPack: Fix PackageMaker .dmg HFS+ creation on macOS APFS hosts
When running hdiutil create
, specify the HFS+ filesystem explicitly.
Otherwise hdiutil
may choose a filesystem based on the host. We do
not want to create APFS images for .dmg
packages because they may not
mount on macOS versions prior to 10.12.
This was missed in !1335 (merged).