[2.2] Linux 6.5 compat: check BLK_OPEN_EXCL is defined

[behlendorf]

Motivation and Context

#15692

Description

On some systems we already have blkdev_get_by_path() with 4 args but still the old FMODE_EXCL and not BLK_OPEN_EXCL defined. The vdev_bdev_mode() function was added to handle this case but there was no generic way to specify exclusive access.

How Has This Been Tested?

Cleanly cherry picked from master, verified by the CI.

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Performance enhancement (non-breaking change which improves efficiency)
• Code cleanup (non-breaking change which makes code smaller or more readable)
• Breaking change (fix or feature that would cause existing functionality to change)
• Library ABI change (libzfs, libzfs_core, libnvpair, libuutil and libzfsbootenv)
• Documentation (a change to man pages or other documentation)

Checklist:

• My code follows the OpenZFS code style requirements.
• I have updated the documentation accordingly.
• I have read the contributing document.
• I have added tests to cover my changes.
• I have run the ZFS Test Suite with this change applied.
• All commit messages are properly formatted and contain Signed-off-by.