Add missing compiler flags and fix warnings (#4889)

This makes the build fail on warnings. It caught two out-of-bounds reads
and a deprecation warning.

hal/src/dev/native/cpp/main.cpp

@@ -8,5 +8,5 @@
 
 int main() {
   fmt::print("Hello World\n");
-  fmt::print("{}\n", HAL_GetRuntimeType());
+  fmt::print("{}\n", static_cast<int32_t>(HAL_GetRuntimeType()));
 }