The cache keys were colliding, causing mayhem.
Add 32-bit unique keys to ImageViews and Samplers, combine them into a unique 64 bit key.

Bug: b/131246679
Change-Id: I74c86a80ee5fec1c97eda720bd0797bff4a1a7e0
Reviewed-on: https://swiftshader-review.googlesource.com/c/SwiftShader/+/29934
Kokoro-Presubmit: kokoro <noreply+kokoro@google.com>
Reviewed-by: Chris Forbes <chrisforbes@google.com>
Reviewed-by: Nicolas Capens <nicolascapens@google.com>
Tested-by: Ben Clayton <bclayton@google.com>