start bpfloader asynchronously

(probably a loss for reliability, but possibly a win for device boot time)

Test: build, atest, TreeHugger
Bug: 150040815
Signed-off-by: Maciej Żenczykowski <maze@google.com>
Original-Change: https://android-review.googlesource.com/1347789
Merged-In: Id62009a9f888ce2092b8a1e7aef24ae4224109d5
Change-Id: Id62009a9f888ce2092b8a1e7aef24ae4224109d5