BoundedPool<> is a fixed capacity pool which blocks when attempting to borrow an item when the pool is empty.

UnboundedPool<> is a automatically growing pool that never blocks.

Useful for building data pipelines.

Bug: b/139010488
Change-Id: Ie1ceec970a866d9d0107247ad2baaced7f024973
Reviewed-on: https://swiftshader-review.googlesource.com/c/SwiftShader/+/34817Tested-by: Ben Clayton <bclayton@google.com>
Reviewed-by: Nicolas Capens <nicolascapens@google.com>
Kokoro-Presubmit: kokoro <noreply+kokoro@google.com>