AppKit: fix debugging problem on Xcode
the problem is that if viewDebuggingEnabled is set in the Scheme, the Xcode debugger behaves
differently from the standard lldb and loads additional frameworks into the running process.
This indirectly includes Cocoa.framework which will load the system AppKit and not recognise
that we have our own.
How this insertion process exactly works is unknown, but disabling viewDebuggingEnabled is
sufficient to stop it. And, we do not loose any debugging capability since we are not compatible
anyways and output to X11

Signed-off-by: H. Nikolaus Schaller <hns@goldelico.com>