replace let_return as suggested by clippy

See also:
https://rust-lang.github.io/rust-clippy/master/index.html#let_and_return

Author: BenWiederhake

src/uu/echo/src/echo.rs

@@ -168,21 +168,17 @@ fn execute(
 }
 
 fn bytes_from_os_string(input: &OsStr) -> Option<&[u8]> {
-    let option = {
-        #[cfg(target_family = "unix")]
-        {
-            use std::os::unix::ffi::OsStrExt;
+    #[cfg(target_family = "unix")]
+    {
+        use std::os::unix::ffi::OsStrExt;
 
-            Some(input.as_bytes())
-        }
-
-        #[cfg(not(target_family = "unix"))]
-        {
-            // TODO
-            // Verify that this works correctly on these platforms
-            input.to_str().map(|st| st.as_bytes())
-        }
-    };
+        Some(input.as_bytes())
+    }
 
-    option
+    #[cfg(not(target_family = "unix"))]
+    {
+        // TODO
+        // Verify that this works correctly on these platforms
+        input.to_str().map(|st| st.as_bytes())
+    }
 }

src/uu/env/src/native_int_str.rs

@@ -283,8 +283,7 @@ impl<'a> NativeStr<'a> {
         match &self.native {
             Cow::Borrowed(b) => {
                 let slice = f_borrow(b);
-                let os_str = slice.map(|x| from_native_int_representation(Cow::Borrowed(x)));
-                os_str
+                slice.map(|x| from_native_int_representation(Cow::Borrowed(x)))
             }
             Cow::Owned(o) => {
                 let slice = f_owned(o);