Fix a race condition in CtClassType#getClassFile3

[michalkurka]

javassist fails to find a (ct)class when concurrently running process
compresses the (ct)class (converts classfile to raw bytes)

the idea of the fix is to make sure to only update rawClassfile and classfile
under lock in getClassFile3, all other places that modify classfile are
already synchronized

when reading the object state, we need to read under lock both classfile and
rawClassFile otherwise we might get an inconsistent state