lfs-multiarch: remove additional options using system rustc

content/post/lfs-multiarch-note.md

@@ -589,8 +589,6 @@ link-shared = true
 # install cargo as well as rust
 extended = true
 target = ["x86_64-unknown-linux-gnu", "i686-unknown-linux-gnu"]
-cargo = "/usr/bin/cargo"
-rustc = "/usr/bin/rustc"
 
 [install]
 prefix = "/usr"