Simple accessor for the breakpoint set.

Bug: b/145351270
Change-Id: Ifb534482009b5842d8bd2a796c082625b770e298
Reviewed-on: https://swiftshader-review.googlesource.com/c/SwiftShader/+/48691
Kokoro-Result: kokoro <noreply+kokoro@google.com>
Reviewed-by: Antonio Maiorano <amaiorano@google.com>
Tested-by: Ben Clayton <bclayton@google.com>