dEQP random tests sometimes add a struct of type:
VK_STRUCTURE_TYPE_DESCRIPTOR_SET_LAYOUT_BINDING_FLAGS_CREATE_INFO_EXT
This cl handles this case gracefully.

Bug b/123244275 b/132185385

Change-Id: I2e0d1af058c33e4014e3ee0e544a95ebf42c9db5
Tests: dEQP-VK.binding_model.descriptorset_random.*
Reviewed-on: https://swiftshader-review.googlesource.com/c/SwiftShader/+/30789
Presubmit-Ready: Alexis Hétu <sugoi@google.com>
Reviewed-by: Nicolas Capens <nicolascapens@google.com>
Reviewed-by: Chris Forbes <chrisforbes@google.com>
Kokoro-Presubmit: kokoro <noreply+kokoro@google.com>
Tested-by: Alexis Hétu <sugoi@google.com>