Fixed crashes in old 32-bit Carbon plugin editor windows when running in macOS Sierra

modules/juce_audio_plugin_client/AU/juce_AU_Wrapper.mm

@@ -2023,7 +2023,11 @@ private:
                 WindowRef windowRef = HIViewGetWindow (parentHIView);
                 hostWindow = [[NSWindow alloc] initWithWindowRef: windowRef];
 
-                [hostWindow retain];
+                // not really sure why this is needed in older OS X versions
+                // but JUCE plug-ins crash without it
+                if ((SystemStats::getOperatingSystemType() & 0xff) < 12)
+                    [hostWindow retain];
+
                 [hostWindow setCanHide: YES];
                 [hostWindow setReleasedWhenClosed: YES];
 

modules/juce_audio_plugin_client/VST/juce_VST_Wrapper.mm

@@ -69,7 +69,7 @@ static pascal OSStatus viewBoundsChangedEvent (EventHandlerCallRef, EventRef, vo
 
 static bool shouldManuallyCloseHostWindow()
 {
-    return getHostType().isCubase7orLater() || getHostType().isRenoise();
+    return getHostType().isCubase7orLater() || getHostType().isRenoise() || ((SystemStats::getOperatingSystemType() & 0xff) >= 12);
 }
 #endif