Runtime can now be set to require relocation

Add a pair of runtime flags -Xrelocate and -Xnorelocate that can force
the runtime to require that all files that are run are relocated, to
prevent attacks based on the known art base address.

Add support for running patchoat on oat files compiled without an image.

Change run-test to have new --prebuild and --relocate flags.

Bug: 15358152

Change-Id: I91166c62dd1ab80e5cbcb7883a2cd0d56afca32d