VOL-1497 : Add more control to kv/memory access

- Added kv locking mechanism (etcd only)
- (watch) control path access whenever possible
- (watch) use a transaction for updates and merge with memory
- cleaned up vendoring
- misc changes to fix exceptions found along the way

Amendments:

- Copyright header got removed in auto-generated file
- Changed default locking to false for KV list operation
- Updated backend api to allow the passing of locking parameter

Change-Id: Ie1a55d3ca8b9d92ae71a85ce42bb22fcf1419e2c
diff --git a/vendor/google.golang.org/grpc/internal/internal.go b/vendor/google.golang.org/grpc/internal/internal.go
index f8932b1..eaa54d4 100644
--- a/vendor/google.golang.org/grpc/internal/internal.go
+++ b/vendor/google.golang.org/grpc/internal/internal.go
@@ -23,14 +23,21 @@
 import "context"
 
 var (
-	// WithContextDialer is exported by clientconn.go
+	// WithContextDialer is exported by dialoptions.go
 	WithContextDialer interface{} // func(context.Context, string) (net.Conn, error) grpc.DialOption
-	// WithResolverBuilder is exported by clientconn.go
+	// WithResolverBuilder is exported by dialoptions.go
 	WithResolverBuilder interface{} // func (resolver.Builder) grpc.DialOption
+	// WithHealthCheckFunc is not exported by dialoptions.go
+	WithHealthCheckFunc interface{} // func (HealthChecker) DialOption
 	// HealthCheckFunc is used to provide client-side LB channel health checking
-	HealthCheckFunc func(ctx context.Context, newStream func() (interface{}, error), reportHealth func(bool), serviceName string) error
+	HealthCheckFunc HealthChecker
+	// BalancerUnregister is exported by package balancer to unregister a balancer.
+	BalancerUnregister func(name string)
 )
 
+// HealthChecker defines the signature of the client-side LB channel health checking function.
+type HealthChecker func(ctx context.Context, newStream func() (interface{}, error), reportHealth func(bool), serviceName string) error
+
 const (
 	// CredsBundleModeFallback switches GoogleDefaultCreds to fallback mode.
 	CredsBundleModeFallback = "fallback"