Fixing wxGLCanvas under 10.14, preparing for layer based drawing

see https://github.com/wxWidgets/wxWidgets/pull/846 , thanks to dkulp

src/osx/glcanvas_osx.cpp

@@ -501,13 +501,8 @@ bool wxGLCanvas::Create(wxWindow *parent,
     // Make a copy of attributes. Will use at wxGLContext ctor
     m_GLAttrs = dispAttrs;
 
-#if wxOSX_USE_IPHONE
     if ( !wxGLCanvas::DoCreate(parent,id,pos,size,style,name) )
         return false;
-#else
-    if ( !wxWindow::Create(parent, id, pos, size, style, name) )
-        return false;
-#endif
     
     return true;
 }