Work around problems with wxGLCanvas resizing under macOS 10.14.5

This OS update has broken resizing of NSOpenGLView, which worked
correctly up until to 10.14.4.

Work around it by preventing the default implementation of update from
being executed. It's not clear why should it help with the problem, but
it does.

Closes https://github.com/wxWidgets/wxWidgets/pull/1354

Closes #18402.

src/osx/cocoa/glcanvas.mm

@@ -149,6 +149,18 @@ WXGLPixelFormat WXGLChoosePixelFormat(const int *GLAttrs,
         impl->doCommandBySelector(aSelector, self, _cmd);
 }
 
+// We intentionally don't call [super update], so suppress the warning about it.
+wxCLANG_WARNING_SUPPRESS(objc-missing-super-calls)
+
+- (void) update
+{
+    // Prevent the base class code from breaking resizing on macOS 10.14.5
+    // (this is not necessary on the older versions, but doesn't seem to do any
+    // harm there neither).
+}
+
+wxCLANG_WARNING_RESTORE(objc-missing-super-calls)
+
 @end
 
 bool wxGLCanvas::DoCreate(wxWindow *parent,