Clean up after cherry-picking commits from firecracker

Signed-off-by: YUAN LYU <lyuyuan92@gmail.com>

src/common/headers.rs

@@ -534,7 +534,10 @@ mod tests {
                 b"Last-Modified: Tue, 15 Nov 1994 12:45:26 GMT\r\nContent-Length: -55\r\n\r\n"
             )
             .unwrap_err(),
-            RequestError::InvalidHeader
+            RequestError::HeaderError(HttpHeaderError::InvalidValue(
+                "Content-Length".to_string(),
+                " -55".to_string()
+            ))
         );
 
         let bytes: [u8; 10] = [130, 140, 150, 130, 140, 150, 130, 140, 150, 160];

src/common/mod.rs

@@ -134,6 +134,7 @@ impl Display for ConnectionError {
 
 /// Errors pertaining to `HttpRoute`.
 #[derive(Debug)]
+#[allow(dead_code)]
 pub enum RouteError {
     /// Handler for http routing path already exists.
     HandlerExist(String),