java/translator: Fix lconst_n truncation

Signed-off-by: Pekka Enberg <penberg@iki.fi>
java/translator: OPC_[fd]const_n

Signed-off-by: Pekka Enberg <penberg@iki.fi>
java/class_file: Float and double constant values

Signed-off-by: Pekka Enberg <penberg@iki.fi>