[VOL-4291] Rw-core updates for gRPC migration

Change-Id: I8d5a554409115b29318089671ca4e1ab3fa98810
diff --git a/vendor/golang.org/x/sys/windows/dll_windows.go b/vendor/golang.org/x/sys/windows/dll_windows.go
index 82076fb..115341f 100644
--- a/vendor/golang.org/x/sys/windows/dll_windows.go
+++ b/vendor/golang.org/x/sys/windows/dll_windows.go
@@ -32,6 +32,8 @@
 
 func (e *DLLError) Error() string { return e.Msg }
 
+func (e *DLLError) Unwrap() error { return e.Err }
+
 // A DLL implements access to a single DLL.
 type DLL struct {
 	Name   string
@@ -389,7 +391,6 @@
 	var flags uintptr
 	if system {
 		if canDoSearchSystem32() {
-			const LOAD_LIBRARY_SEARCH_SYSTEM32 = 0x00000800
 			flags = LOAD_LIBRARY_SEARCH_SYSTEM32
 		} else if isBaseName(name) {
 			// WindowsXP or unpatched Windows machine