error: use of undeclared identifier 'send'

Rev. f16b313 as used from ```chuffed``` breaks:

```
/wrkdirs/usr/ports/math/chuffed/work/chuffed-e04bedd/submodules/cp-profiler-integration/connector.hpp:119:9: error: use of undeclared identifier 'send'
    n = send(s, buf + total, static_cast<size_t>(bytesleft), 0);
        ^
```

OS: FreeBSD 12.2
clang-10

Yuri
