See https://en.cppreference.com/w/cpp/header/cerrno for additional details. Some of used constants are defined in this header.
Inclusion is necessary to avoid these errors:
```
/home/user/IXWebSocket/ixwebsocket/IXNetSystem.cpp:189:30: error: use of undeclared identifier 'EAFNOSUPPORT'
default: errno = EAFNOSUPPORT; return 0;
^
/home/user/IXWebSocket/ixwebsocket/IXNetSystem.cpp:191:17: error: use of undeclared identifier 'ENOSPC'
errno = ENOSPC;
^
/home/user/IXWebSocket/ixwebsocket/IXNetSystem.cpp:175:25: warning: implicit conversion loses integer precision: 'size_t' (aka 'unsigned long long') to 'int' [-Wshorten-64-to-32]
j = strspn(buf + i, ":0");
~ ^~~~~~~~~~~~~~~~~~~~~
/home/user/IXWebSocket/ixwebsocket/IXNetSystem.cpp:234:21: error: use of undeclared identifier 'EAFNOSUPPORT'
errno = EAFNOSUPPORT;
^
2 warnings and 3 errors generated.
```
* Correctly convert remote port bytecode to uint16 port number.
Copied the network_to_host_short function from the ASIO library to convert the remote port byte code to a uint16 number.
* Switched from uint16_t to unsigned short to work in Windows
* Updated missed uint16_t to unsigned short
* Added asynchronous udp receive function
* Remove receive_async and added low level recv, which is non-blocking.
* Remove thread include
* Moved unix include to IXNetSystem.h
* init Net system on Windows
* propagate DNS error
* Add zlib 1.2.11 sources
* link zlib statically for windows
* remove not implemented function declaration
* fix connect on Windows
