feat(ffi): add http1_allow_multiline_headers (#2918)

src/ffi/client.rs

@@ -179,3 +179,16 @@ ffi_fn! {
         hyper_code::HYPERE_OK
     }
 }
+
+ffi_fn! {
+    /// Set whether HTTP/1 connections will accept obsolete line folding for header values.
+    /// Newline codepoints (\r and \n) will be transformed to spaces when parsing.
+    ///
+    /// Pass `0` to disable, `1` to enable.
+    ///
+    fn hyper_clientconn_options_http1_allow_multiline_headers(opts: *mut hyper_clientconn_options, enabled: c_int) -> hyper_code {
+        let opts = non_null! { &mut *opts ?= hyper_code::HYPERE_INVALID_ARG };
+        opts.builder.http1_allow_obsolete_multiline_headers_in_responses(enabled != 0);
+        hyper_code::HYPERE_OK
+    }
+}