Rename org.kxml2 code to com.android.org.kxml2

org.kxml2 code is heavily modified in Android so renaming it to a
reserved package name will not make it less maintainable. This rename
should also flush out users who are depending on the parser
package name.

Bug: 111055375
Test: build
Change-Id: Idfe871ef7b24fd60d706b932ff2dc52eb9fbf4b6