Implemented operator< with std::tie to force strict weak ordering.

Bug b/141863676

Change-Id: If14328922f0c8c62fd92d74f1bcca0c9a2e77f4c
Reviewed-on: https://swiftshader-review.googlesource.com/c/SwiftShader/+/36929
Presubmit-Ready: Alexis Hétu <sugoi@google.com>
Reviewed-by: Nicolas Capens <nicolascapens@google.com>
Kokoro-Presubmit: kokoro <noreply+kokoro@google.com>
Tested-by: Alexis Hétu <sugoi@google.com>