Add support for registering classpath classes status.

By doing class unloading after each dex file compilation, we are loosing
away verification done on classpath classes.

This change introduces a new table for keeping around class status of
classpath classes.

Multidex quickening compilation improved by ~5% by not re-verifying classpath
classes.

Bug: 63467744

test: test.py
test: golem successfully compiles FB
Change-Id: I629c0a7d86519bbc516f5e59f7cd92ca6ca842eb