Specialised a recent OSX window resizing change to only apply on 10.11 or later, due to problems on older OS versions.

modules/juce_gui_basics/native/juce_mac_NSViewComponentPeer.mm

@@ -254,8 +254,13 @@ public:
         }
         else
         {
+            // Repaint behaviour of setFrame seemed to change in 10.11, and the drawing became synchronous,
+            // causing performance issues. But sending an async update causes flickering in older versions,
+            // hence this version check to use the old behaviour on pre 10.11 machines
+            static bool isPre10_11 = SystemStats::getOperatingSystemType() <= SystemStats::MacOSX_10_10;
+
             [window setFrame: [window frameRectForContentRect: flippedScreenRect (r)]
-                     display: false];
+                     display: isPre10_11];
         }
 
         if (oldViewSize.width != r.size.width || oldViewSize.height != r.size.height)