[LU-16363] build fix for fiemap flexible array wiretest

• Type: Bug
• Resolution: Fixed
• Priority: Minor
• Fix Version/s: Lustre 2.16.0
• Severity: 3
• Assignee: Shaun Tancheff
• Reporter: Shaun Tancheff

Description

Linux commit v5.19-rc2-1-g94dfc73e7cf4
treewide: uapi: Replace zero-length arrays with flexible-array
members
Adjust wiretest to handle flexible array when sizeof(fiemap->fm_extents) is undefined.