asan: don't use thread user_id

asan does not use user_id for anything,
so don't pass it to ThreadCreate.
Passing a random uninitialized field of AsanThread
as user_id does not make much sense anyway.

Depends on D113921.

Reviewed By: vitalybuka

Differential Revision: https://reviews.llvm.org/D113922

GitOrigin-RevId: bdabf3c38a2efcbe1b5d28a262cb1b96a08a3156
2 files changed