Only one will be used.

Tests: dEQP-VK.spirv_assembly.instruction.compute.multiple_shaders.*
Bug: b/132341142
Change-Id: I75588f3281f325dc1753222a1f89476267c56ad3
Reviewed-on: https://swiftshader-review.googlesource.com/c/SwiftShader/+/31011
Kokoro-Presubmit: kokoro <noreply+kokoro@google.com>
Presubmit-Ready: Ben Clayton <bclayton@google.com>
Tested-by: Ben Clayton <bclayton@google.com>
Reviewed-by: Nicolas Capens <nicolascapens@google.com>