Merge "memtag_stack: vfork and longjmp support." am: 4ebdeebef7

Original change: https://android-review.googlesource.com/c/platform/bionic/+/2097258

Change-Id: I169579ec60e4f00562fc9a7c1273c7272421e266
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>