We want the partial content goodies of HTTP/1.1 without
requiring persistent connections.  Persistent connections across
multiple HTTP requests don't really help in the case of MPD,
either, because our content is usually big and heavy.

Note: this puts MPD at the hands of the server to correctly
close() the TCP connection we're using.  If we connect to a
rogue server that keeps the connection alive even when request
not to, we'll spin :(  However, encountering such a server
is very unlikely...

git-svn-id: https://svn.musicpd.org/mpd/trunk@6867 09075e82-0dd4-0310-85a5-a0d7c8717e4f