Roll Android's rustc from 1.40.0 to 1.42.0

Also delete now unused 1.40.0
Bug: 152633654

Change-Id: I3a0e755e198bbe23aaa0516d1cca180d6cad3eea
1663 files changed
tree: d0771d0290a42e194936df84b7ee2282bad241dc
  1. bootstrap/
  2. darwin-x86/
  3. linux-x86/
  4. OWNERS