Wrap google DNS fallback property

OpenVPN Adapter/OpenVPNConfiguration.h

@@ -69,4 +69,10 @@ typedef NS_ENUM(NSInteger, IPv6Preference) {
  */
 @property (nonatomic) BOOL tunPersist;
 
+/**
+ If true and a redirect-gateway profile doesn't also define
+ DNS servers, use the standard Google DNS servers.
+ */
+@property (nonatomic) BOOL googleDNSFallback;
+
 @end

OpenVPN Adapter/OpenVPNConfiguration.mm

@@ -141,4 +141,12 @@ using namespace openvpn;
     _config.tunPersist = tunPersist;
 }
 
+- (BOOL)googleDNSFallback {
+    return _config.googleDnsFallback;
+}
+
+- (void)setGoogleDNSFallback:(BOOL)googleDNSFallback {
+    _config.googleDnsFallback = googleDNSFallback;
+}
+
 @end