Share compilation and copy independent commands and source into new worlds

userland/coreutils/src/bin/expr.rs

@@ -0,0 +1,5 @@
+//! Implements the expr command as an independent WASI binary.
+fn main() {
+    uucore::locale::setup_localization("expr").expect("utility supplies localization");
+    std::process::exit(uu_expr::uumain(uucore::args_os()));
+}