Revert "Work around problems with wxGLCanvas resizing under macOS 10.14.5"

This reverts commit ea68934b8e as it
didn't fix the problem in all cases -- an alternative fix will replace
it in the upcoming commits.

src/osx/cocoa/glcanvas.mm

@@ -149,18 +149,6 @@ 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,