Reactor: Fix cast from bool -> RValue<Bool>.

Reactor: Fix cast from bool -> RValue<Bool>.

This was previously taking the IntLiteral<T> path, resulting in an integer type instead of a bool type.

Bug: b/128636885
Change-Id: I1a36a7ba0e7009431dc44645f90454d389be721b
Reviewed-on: https://swiftshader-review.googlesource.com/c/SwiftShader/+/27250
Presubmit-Ready: Ben Clayton <bclayton@google.com>
Kokoro-Presubmit: kokoro <noreply+kokoro@google.com>
Tested-by: Ben Clayton <bclayton@google.com>
Reviewed-by: Nicolas Capens <nicolascapens@google.com>