This commit adds an implementation for "socket.sendall" to the Unix
port.
Right now the implementation is a wrapper over a single "socket.send"
call, since it wasn't possible to let "socket.send" perform a partial
transfer. With no partial transfers it is not possible to have a
testable implementation following the expected behaviour, so a single
send operation is done and OSErr(EINTR) is raised if a partial transfer
occurs.
The discussion for the issue linked to this PR contains more information
about the efforts made to let partial transfers happen.
This fixes#16803.
Signed-off-by: Alessandro Gatti <a.gatti@frob.it>
Alessandro Gatti