DebugInfo::NotifyObjectEmitted and NotifyFreeingObject
have become statics as the free-object callback happens
after the DebugInfo instance is destroyed. This isn't
an issue as the JITEventListener is a singleton in LLVM.

Bug: b/133399620
Change-Id: I93fa73d0e416ba3c09c6550cc0d3abd56354e862
Reviewed-on: https://swiftshader-review.googlesource.com/c/SwiftShader/+/31837Tested-by: Ben Clayton <bclayton@google.com>
Reviewed-by: Nicolas Capens <nicolascapens@google.com>
Kokoro-Presubmit: kokoro <noreply+kokoro@google.com>