Fix off-by-one bug in range tree code

[pcd1193182]

Sponsored-by: Klara, Inc.
Sponsored-by: Wasabi Technology, Inc.

Motivation and Context

Without this fix, zfs_range_tree_find_in could return an overlap when the found range starts immediately after the searched range, with no actual overlap. For example, a tree with only a range from 10 to 14 inclusive (start 10, size 5), would return an overlap if you called zfs_range_tree_find_in(rt, 0, 10, ...)

Description

Fix the bug by changing to >= instead of >.

How Has This Been Tested?

Tested in conjunction with a new utility I've been developing that isn't quite ready for release yet.

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)
• Quality assurance (non-breaking change which makes the code more robust against bugs)
• 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.