script: OP_PUBKEY, OP_PUBKEYHASH are placeholders

these opcodes don't actually push anything, they are only used in a bitcoind
templating routine:
https://github.com/bitcoin/bitcoin/blob/0.9.2/src/script.cpp#L1198

they  behave like OP_INVALIDOPCODE otherwise:
https://github.com/bitcoin/bitcoin/blob/0.9.2/src/test/data/script_valid.json#L272