Holds the global debugger state.

Bug: b/145351270
Change-Id: I4e483c145af068755716f23c09adcc68d138ceaa
Reviewed-on: https://swiftshader-review.googlesource.com/c/SwiftShader/+/38898Reviewed-by: Nicolas Capens <nicolascapens@google.com>
Tested-by: Ben Clayton <bclayton@google.com>
Kokoro-Presubmit: kokoro <noreply+kokoro@google.com>