Execute_mnemonic() is changed so it won't loop when it can't find the assembly-mnemonic in the as_table.
Execute_mnemonic() is changed so it won't loop when it can't find the
assembly-mnemonic in the as_table.

Godzil/ack,Godzil/ack,Godzil/ack,Godzil/ack,Godzil/ack