... even if they're not directly used by the SPIR-V shader code.
This will let the debugger display these values in the locals window.

Bug: b/145351270
Change-Id: I1d390e95bf38e89b072ef374e6a35cd8222a45c6
Reviewed-on: https://swiftshader-review.googlesource.com/c/SwiftShader/+/38912Tested-by: Ben Clayton <bclayton@google.com>
Presubmit-Ready: Ben Clayton <bclayton@google.com>
Kokoro-Presubmit: kokoro <noreply+kokoro@google.com>
Reviewed-by: Nicolas Capens <nicolascapens@google.com>