Fix rustls-webpki feature

#1965 modified the initialization
code for HttpClient in a way that prevents it from building with the
`rustls-webpki` feature enabled. Fix that, so that building with
rustls-webpki works again.

rusoto/core/src/request.rs

@@ -223,7 +223,7 @@ impl HttpClient {
         #[cfg(feature = "native-tls")]
         let connector = HttpsConnector::new();
 
-        #[cfg(feature = "rustls")]
+        #[cfg(any(feature = "rustls", feature = "rustls-webpki"))]
         let connector = {
             let builder = crate::tls::HttpsConnectorBuilder::new();
 
@@ -243,7 +243,7 @@ impl HttpClient {
         #[cfg(feature = "native-tls")]
         let connector = HttpsConnector::new();
 
-        #[cfg(feature = "rustls")]
+        #[cfg(any(feature = "rustls", feature = "rustls-webpki"))]
         let connector = {
             let builder = crate::tls::HttpsConnectorBuilder::new();