netd: Enable clang-tidy and fix all warnings

Bug: 65246407
Test: m netd && system/netd/tests/runtests.sh
Change-Id: I1d22b2bc317fe7218ccde78859ed0623d6a1f8df
diff --git a/server/NetlinkHandler.cpp b/server/NetlinkHandler.cpp
index d0aafde..928e329 100644
--- a/server/NetlinkHandler.cpp
+++ b/server/NetlinkHandler.cpp
@@ -162,6 +162,7 @@
     }
 }
 
+// NOLINTNEXTLINE(cert-dcl50-cpp): Grandfathered C-style variadic function.
 void NetlinkHandler::notify(int code, const char *format, ...) {
     char *msg;
     va_list args;