asio: Copy streambuf to our buffer by blocks.
asio: Copy streambuf to our buffer by blocks.

The previous code that read character by character was limiting
bandwidth to 50Ko/s on an arm 200MHz CPU.

	* include/libport/asio.hxx(Socket::onRead_): Copy source
	  streambuf to our string buffer by blocks of fixed size.

aldebaran/libport,aldebaran/libport,aldebaran/libport,aldebaran/libport,aldebaran/libport