Eliminate unused private field (compiler warning).

node/SysEnv.cpp

@@ -62,8 +62,7 @@
 
 namespace ZeroTier {
 
-SysEnv::SysEnv(const RuntimeEnvironment *renv) :
-	_r(renv)
+SysEnv::SysEnv(const RuntimeEnvironment *renv)
 {
 }
 

node/SysEnv.hpp

@@ -49,9 +49,6 @@ public:
 	 * @return Fingerprint of currently running network environment
 	 */
 	uint64_t getNetworkConfigurationFingerprint();
-
-private:
-	const RuntimeEnvironment *_r;
 };
 
 } // namespace ZeroTier