viewWillDraw crashes on OSX 10.11

Hi Juce team,

Following recent changes I get a crash on 10.11 in viewWillDraw
I use the 10.12 SDK but with a deployment target of 10.9
addMethod (@selector (viewWillDraw), viewWillDraw, "v@:");
should be using ifdef as well ?

Any idea ?

Thanks !

I was able to reproduce the crash using a slightly different combination of SDK and runtime platform. Could you please check that this commit addresses the issue?

That did the trick.

Thanks !