fix for failed reads when client.local_extents=1

[MichaelBrim]

Description

Fixes a couple bugs in the client-local read path that prevented local read operations from completing successfully.

Motivation and Context

Unit tests and example runs were failing when setting UNIFYFS_CLIENT_LOCAL_EXTENTS=1

How Has This Been Tested?

Tested on OLCF Summit and in Ubuntu Docker

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)
• Testing (addition of new tests or update to current tests)
• Documentation (a change to man pages or other documentation)

Checklist:

• My code follows the UnifyFS code style requirements.
• I have updated the documentation accordingly.
• I have read the CONTRIBUTING document.
• I have added tests to cover my changes.
• All new and existing tests passed.
• All commit messages are properly formatted.

[MichaelBrim]

@adammoody please look over and merge asap

[adammoody]

Thanks @MichaelBrim and @CamStan