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/DumpWriter.cpp b/server/DumpWriter.cpp
index 44e5e9e..ef3ffc8 100644
--- a/server/DumpWriter.cpp
+++ b/server/DumpWriter.cpp
@@ -59,6 +59,7 @@
     ::write(mFd, "\n", 1);
 }
 
+// NOLINTNEXTLINE(cert-dcl50-cpp): Grandfathered C-style variadic function.
 void DumpWriter::println(const char* fmt, ...) {
     std::string line;
     va_list ap;