Nightly/newer versions of llvm-binutils no longer recognize `--arch-name`

[StripedMonkey]

In following the embedonomicon I discovered that cargo objdump --bin app -- -d -no-show-raw-insn no longer works, for two reasons

1. llvm-objdump no longer accepts --arch-name
2. -no-show-raw-insn must have two -s instead of one on stable.

This is on https://docs.rust-embedded.org/embedonomicon/memory-layout.html#inspecting-it