The swapchain images were being freed with an allocator
despite never being created with one.

Tests: dEQP-VK.wsi.xlib.swapchain.simulate_oom.*
Bug: b/132451407
Change-Id: I26c6ecd18d04f514cdae171100de6a89c919a777
Reviewed-on: https://swiftshader-review.googlesource.com/c/SwiftShader/+/31692
Presubmit-Ready: Ben Clayton <bclayton@google.com>
Kokoro-Presubmit: kokoro <noreply+kokoro@google.com>
Reviewed-by: Chris Forbes <chrisforbes@google.com>
Tested-by: Hernan Liatis <hliatis@google.com>