Glib config test: fix compiler warnings

Remove warnings: "assigned but not used" and "uninitialized usage".

Change-Id: I247e1de020e78c35787b8e1e30421174ac232fd5
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
Fix tst_QUdpSocket::multicastLeaveAfterClose

With IPv6, you cannot bind to a multicast address. You need to bind to a
local address only. The previous tests either checked this or didn't
check the result of bind().

Change-Id: Ief70887d8988fc1bc4394cf6ff34b5d560e5748e
Reviewed-by: Richard J. Moore <rich@kde.org>
Silence warning in tst_QUdpSocket::multicast for Any+IPv4

QUdpSocket doesn't support binding to QHostAddress::Any and then joining
an IPv4 multicat group since QHostAddress::Any is really an IPv6 socket
with v6only = false. The test did check this case, but failed to ignore
the warning.

Change-Id: I62d782408319a6e566e0ff1a6081b706ac1f669c
Reviewed-by: Richard J. Moore <rich@kde.org>