Enable gen_log for DnsResolverService and fix some style problems

1. enable gen_log in DnsResolverService
2. fix style problems in DnsResolverService
3. fix potential log_func register bug which is service is registered earlier
   than logFunc in NetdNativeService

Test: built, flashed, booted
      system/netd/tests/runtests.sh pass

Change-Id: Ib046b52065f894cd5bac0c9c905b85352556a48d
diff --git a/server/NetdNativeService.h b/server/NetdNativeService.h
index 86d4b73..68c9886 100644
--- a/server/NetdNativeService.h
+++ b/server/NetdNativeService.h
@@ -29,6 +29,7 @@
 
 class NetdNativeService : public BinderService<NetdNativeService>, public BnNetd {
   public:
+    NetdNativeService();
     static status_t start();
     static char const* getServiceName() { return "netd"; }
     virtual status_t dump(int fd, const Vector<String16> &args) override;