VOL-4217: Update to latest version of protos and voltha-lib-go for
voltha-2.9 release. Tested with BAL3.10

Change-Id: Ibdc5978a1f2df713965a27ce26d0e22c1ffa366a
diff --git a/vendor/golang.org/x/net/http2/headermap.go b/vendor/golang.org/x/net/http2/headermap.go
index c3ff3fa..9e12941 100644
--- a/vendor/golang.org/x/net/http2/headermap.go
+++ b/vendor/golang.org/x/net/http2/headermap.go
@@ -6,7 +6,6 @@
 
 import (
 	"net/http"
-	"strings"
 	"sync"
 )
 
@@ -79,10 +78,10 @@
 	}
 }
 
-func lowerHeader(v string) string {
+func lowerHeader(v string) (lower string, ascii bool) {
 	buildCommonHeaderMapsOnce()
 	if s, ok := commonLowerHeader[v]; ok {
-		return s
+		return s, true
 	}
-	return strings.ToLower(v)
+	return asciiToLower(v)
 }