Also, make the analogous change to apple/swift-driver#1372, which gets the
sanitizer tests working on Android again, and remove the lld_lto feature in the
tests, which is now unused.
Also, make some related changes, like updating a path in the Android doc, making sure the
`unknown` vendor is always used, and using `CPU` instead of `CODEGENERATOR`.
`Swift` is the name of the Swift standard library module. Creating another module with this name breaks assumptions in the compiler and caused these two tests to fail.
