`IoUringZeroCopyBufferPool` depends on unreleased liburing features

# Problem Definition

Folly recently added a `IoUringZeroCopyBufferPool` class in 70669ee. However, this class depends on definitions from a liburing version that hasn't been released yet. This is causing issues with packaging Folly.

# Solution

Please add a configure check or build-time flag for a liburing version that supports zcrx.

CC @spikeh since this was part of your changes.

Start with the IoUringZeroCopyBufferPool class added in commit 70669ee and trace the build configuration that exposes its liburing definitions. Check how Folly detects liburing capabilities, then verify that packaging succeeds with released liburing while zcrx support is gated by a configure check or build-time flag.

Written by the indexing model from the issue text.