Enable init checker

clang-tidy added cppcoreguidelines-init-variables as a check, which is
something we already enforce to some extent, but getting CI to enforce
it will help reviews move faster.

Tested: Code compiles.  Noop changes.

Signed-off-by: Ed Tanous <edtanous@google.com>
Change-Id: I7e10950de617b1d3262265572b1703f2e60b69d0
diff --git a/include/async_resolve.hpp b/include/async_resolve.hpp
index 105616d..563d816 100644
--- a/include/async_resolve.hpp
+++ b/include/async_resolve.hpp
@@ -73,7 +73,7 @@
                         handler(ec, endpointList);
                         return;
                     }
-                    uint16_t portNum;
+                    uint16_t portNum = 0;
                     auto it = std::from_chars(
                         port.data(), port.data() + port.size(), portNum);
                     if (it.ec != std::errc())