[JVMCI] InstalledCode.deoptimize(false) should not touch address field

The ability to make an nmethod non-entrant via an InstalledCode object was added by JDK-8292917. However, the implementation also clears the InstalledCode.address field. This severs the connection between an InstalledCode object an its nmethod. This makes it impossible for users of the InstalledCode object to do things like subsequently deoptimize the nmethod which may be necessary if assumptions used when compiling the nmethod are invalidated (a common case in Truffle).

The fix is to only clear the InstalledCode.address field when calling InstalledCode.invalidate(true).