Avoid adding empty arguments

QByteArray split does create one item even if the string is empty.
Hence check if the launch arguments string needs to be parsed at all.

Change-Id: I0a355212aaa7254fe0f417c61a59c30223311915
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@digia.com>
Ignore debugger arguments on WinRT

Visual Studio debuggers send an argument to specify the debugger port.
This argument needs to be skipped while parsing and not to be interpreted
as an option or test function.

Change-Id: I24efb52fbd668a7bc3388c876f5ea0d950de1d5b
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@digia.com>