Fixed ArpLayer zeroing only the first 8 bytes of the buffer, instead …

…of the entire buffer.

Packet++/src/ArpLayer.cpp

@@ -13,7 +13,7 @@ namespace pcpp
 		constexpr size_t headerLen = sizeof(arphdr);
 		m_DataLen = headerLen;
 		m_Data = new uint8_t[headerLen];
-		memset(m_Data, 0, sizeof(headerLen));
+		memset(m_Data, 0, headerLen);
 		m_Protocol = ARP;
 
 		arphdr* arpHeader = getArpHeader();