QNativeSocketEngine: use stream-style qDebug to fix a warning about FD types.

FD types differ depending on the platform, so using the stream form is the
easiest way to make this work.

Change-Id: I00b1a303f3d865fe5e89ba97bd438c51c6cd8f09
Reviewed-by: Richard J. Moore <rich@kde.org>
QNativeSocketEngine: Add debug in createNewSocket.

If this fails, we want to know about it when trying to debug.

Change-Id: I33f05186e93fcd9284a7e7c609d00fe7ac87cd4e
Reviewed-by: Richard J. Moore <rich@kde.org>
Rename globalShareContext to qt_gl_global_share_context

This makes it easier to forward-declare the exported symbol from
other Qt modules without having to include the private headers.

This keeps the old API until dependent submodules are updated.

Change-Id: I08310a684b79f2f612f2ce897a601ff74178bee6
Reviewed-by: Laszlo Agocs <laszlo.agocs@digia.com>