[C++] Fix clang -Wnewline-eof warning (#7711)

* Fix clang -Wnewline-eof warning

* Enable -Wnewline-eof warning

Co-authored-by: Derek Bailey <derekbailey@google.com>

src/bfbs_gen_lua.cpp

@@ -630,4 +630,4 @@ std::unique_ptr<BfbsGenerator> NewLuaBfbsGenerator(
   return std::unique_ptr<LuaBfbsGenerator>(new LuaBfbsGenerator(flatc_version));
 }
 
-}  // namespace flatbuffers
+}  // namespace flatbuffers