Clear mod-union tables for immune spaces in PreZygoteFork am: 157084ac62

Original change: https://android-review.googlesource.com/c/platform/art/+/2390333

Change-Id: Idbeb93f7701a8da812e7df4006813adeb0f7d601
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>