TUN-6937: Bump golang.org/x/* packages to new release tags

vendor/golang.org/x/net/http2/headermap.go

@@ -27,7 +27,14 @@ func buildCommonHeaderMaps() {
 		"accept-language",
 		"accept-ranges",
 		"age",
+		"access-control-allow-credentials",
+		"access-control-allow-headers",
+		"access-control-allow-methods",
 		"access-control-allow-origin",
+		"access-control-expose-headers",
+		"access-control-max-age",
+		"access-control-request-headers",
+		"access-control-request-method",
 		"allow",
 		"authorization",
 		"cache-control",
@@ -53,6 +60,7 @@ func buildCommonHeaderMaps() {
 		"link",
 		"location",
 		"max-forwards",
+		"origin",
 		"proxy-authenticate",
 		"proxy-authorization",
 		"range",
@@ -68,6 +76,8 @@ func buildCommonHeaderMaps() {
 		"vary",
 		"via",
 		"www-authenticate",
+		"x-forwarded-for",
+		"x-forwarded-proto",
 	}
 	commonLowerHeader = make(map[string]string, len(common))
 	commonCanonHeader = make(map[string]string, len(common))
@@ -85,3 +95,11 @@ func lowerHeader(v string) (lower string, ascii bool) {
 	}
 	return asciiToLower(v)
 }
+
+func canonicalHeader(v string) string {
+	buildCommonHeaderMapsOnce()
+	if s, ok := commonCanonHeader[v]; ok {
+		return s
+	}
+	return http.CanonicalHeaderKey(v)
+}