stream: Use MSG_NOSIGNAL flag if available for send().

This avoids MPlayer quitting due to SIGPIPE at least for these cases.
Ignoring SIGPIPE in general would break window-closing with some
window-managers.

git-svn-id: svn://svn.mplayerhq.hu/mplayer/trunk@31566 b3059339-0415-0410-9bf9-f77b7e298cf2