This initializes arrays to hold the descriptor sets in the routine. Nothing uses this yet.

Bug: b/126330097
Change-Id: If052d0b93e62e4f32e88ed02f9bc21f4203587f5
Reviewed-on: https://swiftshader-review.googlesource.com/c/SwiftShader/+/25553Reviewed-by: Alexis Hétu <sugoi@google.com>
Reviewed-by: Nicolas Capens <nicolascapens@google.com>
Tested-by: Ben Clayton <bclayton@google.com>