Remove structopt where appropriate

Signed-off-by: Alek Ratzloff <alekratz@gmail.com>

src/libvm/Cargo.toml

@@ -9,7 +9,6 @@ build = "build.rs"
 # See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
 
 [dependencies]
-structopt = "0.3"
 bitflags = "1"
 byteorder = "1"
 lazy_static = "1"