channel_read: force window adjusts!

if there's not enough room to receive the data that's being requested,
the window adjustment needs to be sent to the remote and thus the force
option has to be used. _libssh2_channel_receive_window_adjust() would
otherwise "queue" small window adjustments for a later packet but that
is really terribly for the small buffer read that for example is the
final little piece of a very large file as then there is no logical next
packet!

Reported by: Armen Babakhanian
Bug: http://www.libssh2.org/mail/libssh2-devel-archive-2012-03/0130.shtml

src/channel.c

@@ -1898,7 +1898,7 @@ libssh2_channel_read_ex(LIBSSH2_CHANNEL *channel, int stream_id, char *buf,
     if(buflen > recv_window) {
         BLOCK_ADJUST(rc, channel->session,
                      _libssh2_channel_receive_window_adjust(channel, buflen,
-                                                            0, NULL));
+                                                            1, NULL));
     }
 
     BLOCK_ADJUST(rc, channel->session,