The mask was previously dropped on the floor here, and the imageview's
only mask used instead. This would produce incorrect results when a
renderpass begin operation had different load ops for depth vs stencil aspect.

Bug: b/128715612
Change-Id: I2bf4051e16c027737b65cd5bc5193a94cf891c36
Reviewed-on: https://swiftshader-review.googlesource.com/c/SwiftShader/+/27428Tested-by: Chris Forbes <chrisforbes@google.com>
Presubmit-Ready: Chris Forbes <chrisforbes@google.com>
Reviewed-by: Nicolas Capens <nicolascapens@google.com>
Kokoro-Presubmit: kokoro <noreply+kokoro@google.com>