Clear mod-union tables for immune spaces in PreZygoteFork am: 157084ac62 am: 2eaf72a47c

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

Change-Id: I795ad6b0a546090dd40b547bcbc780a4fc0740d7
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>