Correct checks for gradient stop position.

It may be <= 1 in the final version and not < 1.

See #11897.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@63866 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

include/wx/graphics.h

@@ -323,7 +323,7 @@ public:
     float GetPosition() const { return m_pos; }
     void SetPosition(float pos)
     {
-        wxASSERT_MSG( pos >= 0 && pos < 1, "invalid gradient stop position" );
+        wxASSERT_MSG( pos >= 0 && pos <= 1, "invalid gradient stop position" );
 
         m_pos = pos;
     }