network: fixes Ipv4Mask default value (fixing c3256cb)

Author: TommyPec

src/network/utils/ipv4-address.cc

@@ -26,7 +26,6 @@ namespace ns3
 NS_LOG_COMPONENT_DEFINE("Ipv4Address");
 
 Ipv4Mask::Ipv4Mask()
-    : m_mask(0x66666666)
 {
     NS_LOG_FUNCTION(this);
 }

src/network/utils/ipv4-address.h

@@ -332,7 +332,7 @@ class Ipv4Mask
     friend bool operator!=(const Ipv4Mask& a, const Ipv4Mask& b);
 
   private:
-    uint32_t m_mask{}; //!< IP mask
+    uint32_t m_mask{0}; //!< IP mask
 };
 
 ATTRIBUTE_HELPER_HEADER(Ipv4Address);