move extern "C"

only JNI functions need to be exported

java/jni/com_zerotierone_sdk_Node.cpp

@@ -40,10 +40,6 @@
 // global static JNI Lookup Object
 JniLookup lookup;
 
-#ifdef __cplusplus
-extern "C" {
-#endif
-
 namespace {
     struct JniRef
     {
@@ -732,6 +728,10 @@ namespace {
     }
 }
 
+#ifdef __cplusplus
+extern "C" {
+#endif
+
 JNIEXPORT jint JNICALL JNI_OnLoad(JavaVM *vm, void *reserved)
 {
     lookup.setJavaVM(vm);