Added struct definitions to JITEngine.
Added struct definitions to JITEngine.

Just allows us to define structs, not use them yet.

Change-Id: I7e59972f3d155cb3d9df54ef7d2a4218a800fae1
Reviewed-on: https://wn-project.dnsalias.net/gerrit/175
Try: Andrew Woloszyn <2926f0436f8103ab8257713335cf26447d8bf68a@google.com>
Tested-by: WNBot <efa0942020584fb66fb8bea377b59e48fa0f85ef@gmail.com>
Reviewed-by: Devon Powell <bef84a74f4a3947934cc58306a6aae518eaf1936@gmail.com>

WNProject/WNFramework,WNProject/WNFramework,WNProject/WNFramework,WNProject/WNFramework