Remove kDex2OatHostKey from oat-header

The oat-header used to include the ISA of the dex2oat used to compile
the image. This made cross-compiling a bitwise identical oat/image
file impossible and is not terribly useful so it was removed.

Test: ./test.py --host
Bug: 119332327
Change-Id: If9d21b5997907ee01283d1345749a01e2a2359ea
2 files changed