See the referenced bug for the gory details. For now, this makes it so
that Subzero's codegen doesn't crash even in the simple ReactorUnitTest
cases.

Bug: b/171222930
Change-Id: Ie22a91d7e3e4f3d940b7b9120067469ac4264020
Reviewed-on: https://swiftshader-review.googlesource.com/c/SwiftShader/+/49388
Kokoro-Result: kokoro <noreply+kokoro@google.com>
Tested-by: Antonio Maiorano <amaiorano@google.com>
Reviewed-by: Nicolas Capens <nicolascapens@google.com>