chore(tonic): Remove duplicated code (#1267)

tonic/src/body.rs

@@ -14,8 +14,6 @@ where
     body.map_err(crate::Status::map_error).boxed_unsync()
 }
 
-// this also exists in `crate::codegen` but we need it here since `codegen` has
-// `#[cfg(feature = "codegen")]`.
 /// Create an empty `BoxBody`
 pub fn empty_body() -> BoxBody {
     http_body::Empty::new()

tonic/src/codegen.rs

@@ -23,8 +23,4 @@ pub mod http {
     pub use http::*;
 }
 
-pub fn empty_body() -> crate::body::BoxBody {
-    http_body::Empty::new()
-        .map_err(|err| match err {})
-        .boxed_unsync()
-}
+pub use crate::body::empty_body;