Also avoid any reading code to be executed in a slot connected to
readyRead() signal because Qt will not emit readyRead() signal
recursively. This change is needed to make Akonadi work on Windows,
because the blocking QLocalSocket::waitForReadyRead() does not work
reliably there.

On Linux QLocalSocket::waitForReadyRead() is used internally only
in DataStream for performance reasons. On Windows DataStream will
internally instantiate a QEventLoop and wait for the readyRead()
signal, which is more expensive, especially since DataStream can
get into the wait state multiple times while reading a single
command.