This, with riscv-fesvr modifications, enables the rocket-chip emulator
to understand (and error out) if a command line argument that will
eventually be consumed by HTIF looks bad and can error out quickly.
This relies on modifications to risc-fesvr to support getopt and the
exposure of what HTIF arguments exist via the `htif.h` header.
Schuyler Eldridge
1aa87f6578