Fix incorrect &*var clones

Thank you @icholy for identifying these in
https://github.com/nhooyr/websocket/pull/259#issuecomment-702279421

dial.go

@@ -250,7 +250,8 @@ func verifyServerExtensions(copts *compressionOptions, h http.Header) (*compress
 		return nil, fmt.Errorf("WebSocket protcol violation: unsupported extensions from server: %+v", exts[1:])
 	}
 
-	copts = &*copts
+	_copts := *copts
+	copts = &_copts
 
 	for _, p := range ext.params {
 		switch p {

internal/test/wstest/pipe.go

@@ -24,7 +24,8 @@ func Pipe(dialOpts *websocket.DialOptions, acceptOpts *websocket.AcceptOptions)
 	if dialOpts == nil {
 		dialOpts = &websocket.DialOptions{}
 	}
-	dialOpts = &*dialOpts
+	_dialOpts := *dialOpts
+	dialOpts = &_dialOpts
 	dialOpts.HTTPClient = &http.Client{
 		Transport: tt,
 	}