vk::destroy was crashing for vk::Fence after:
https://swiftshader-review.googlesource.com/c/SwiftShader/+/31988

Reverted that change and fixed it in VkObject.cpp to make sure the
result of the cast is always equal to the allocated memory.

Bug: b/117835459
Change-Id: I831625418fc83503329e833d48d9765b75d83b80
Reviewed-on: https://swiftshader-review.googlesource.com/c/SwiftShader/+/31990Tested-by: Alexis Hétu <sugoi@google.com>
Presubmit-Ready: Alexis Hétu <sugoi@google.com>
Reviewed-by: Antonio Maiorano <amaiorano@google.com>
Reviewed-by: Nicolas Capens <nicolascapens@google.com>
Kokoro-Presubmit: kokoro <noreply+kokoro@google.com>