fix(http1): ignore chunked trailers (#2357)

Previously, hyper returned an "Invalid chunk end CR" error on chunked
responses with trailers, as described in RFC 7230 Section 4.1.2. This
commit adds code to ignore the trailers.

Closes #2171

tests/client.rs

@@ -430,6 +430,69 @@ test! {
             body: None,
 }
 
+test! {
+    name: client_get_req_body_chunked_with_trailer,
+
+    server:
+        expected: "\
+            GET / HTTP/1.1\r\n\
+            host: {addr}\r\n\
+            \r\n\
+            ",
+        reply: "\
+            HTTP/1.1 200 OK\r\n\
+            Transfer-Encoding: chunked\r\n\
+            \r\n\
+            5\r\n\
+            hello\r\n\
+            0\r\n\
+            Trailer: value\r\n\
+            \r\n\
+            ",
+
+    client:
+        request: {
+            method: GET,
+            url: "http://{addr}/",
+        },
+        response:
+            status: OK,
+            headers: {},
+            body: &b"hello"[..],
+}
+
+test! {
+    name: client_get_req_body_chunked_with_multiple_trailers,
+
+    server:
+        expected: "\
+            GET / HTTP/1.1\r\n\
+            host: {addr}\r\n\
+            \r\n\
+            ",
+        reply: "\
+            HTTP/1.1 200 OK\r\n\
+            Transfer-Encoding: chunked\r\n\
+            \r\n\
+            5\r\n\
+            hello\r\n\
+            0\r\n\
+            Trailer: value\r\n\
+            another-trainer: another-value\r\n\
+            \r\n\
+            ",
+
+    client:
+        request: {
+            method: GET,
+            url: "http://{addr}/",
+        },
+        response:
+            status: OK,
+            headers: {},
+            body: &b"hello"[..],
+}
+
 test! {
     name: client_get_req_body_sized,