message: [mdns] simplify struct construction with default member initializer
diff: @@ -97,26 +97,14 @@ public:
  */
  struct DiscoveredInstanceInfo
  {
  - /**
  - * Constructor to initialize a `DiscoveredInstanceInfo` instance.
  - *
  - */
  - DiscoveredInstanceInfo(void)
  - : mPort(0)
  - , mPriority(0)
  - , mWeight(0)
  - , mTtl(0)
  - {
  - }
  -
  std::string mName; ///< Instance name.
  std::string mHostName; ///< Full host name.
  std::vector<Ip6Address> mAddresses; ///< IPv6 addresses.
  - uint16_t mPort; ///< Port.
  - uint16_t mPriority; ///< Service priority.
  - uint16_t mWeight; ///< Service weight.
  + uint16_t mPort = 0; ///< Port.
  + uint16_t mPriority = 0; ///< Service priority.
  + uint16_t mWeight = 0; ///< Service weight.
  std::vector<uint8_t> mTxtData; ///< TXT RDATA bytes.
  - uint32_t mTtl; ///< Service TTL.
  + uint32_t mTtl = 0; ///< Service TTL.
  };
  /**
  @@ -125,18 +113,9 @@ public:
  */
  struct DiscoveredHostInfo
  {
  - /**
  - * Constructor to initialize a `DiscoveredHostInfo` instance.
  - *
  - */
  - DiscoveredHostInfo(void)
  - : mTtl(0)
  - {
  - }
  -
  std::string mHostName; ///< Full host name.
  std::vector<Ip6Address> mAddresses; ///< IP6 addresses.
  - uint32_t mTtl; ///< Host TTL.
  + uint32_t mTtl = 0; ///< Host TTL.
  };
  /**
  