Merge "simpleperf: check invalid pid in ForkThread()." am: 1e427d7d5d am: a84b20aeee

Original change: https://android-review.googlesource.com/c/platform/system/extras/+/2356863

Change-Id: I4e74808ae03957971645ea31c73302f137e6e6f1
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>