std.fs.net.Stream: add writev and writevAll

I noticed that the write function does not properly use non-blocking
I/O. This file needs to be reworked for evented I/O to properly take
advantage of non-blocking writes to network sockets.
68e7726478Andrew Kelley committed on 2/16/2021, 6:01:17 PMparent9270aae
2 files changedLine totals unavailable