Automatic use of MSG_NOSIGNAL or SO_NOSIGPIPE (checked at compile time); moved enabli...

Automatic use of MSG_NOSIGNAL or SO_NOSIGPIPE (checked at compile time); moved enabling of connection events on Darwin after connection has been accepted in WaitConnection; in Connect, enable events only after connection has succeeded rather than unconditionally before; do not close connection when a socket call results in EWOULDBLOCK, EAGAIN or EINTR, as these do not indicate a closed connection; loop around calls to send and recv so that socket calls returning EINTR can be immediately retried; check for invalid socket pointer in Detected_Read

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@32697 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775