Fix wxWrapSizer minimal size calculation.

Add a unit test checking that wxWrapSizer::CalcMin() returns the expected
results.

Closes #12464.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@66862 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

include/wx/sizer.h

@@ -665,6 +665,10 @@ public:
         m_position = pos;
         m_size = size;
         Layout();
+
+        // This call is required for wxWrapSizer to be able to calculate its
+        // minimal size correctly.
+        InformFirstDirection(wxHORIZONTAL, size.x, size.y);
     }
     void SetDimension(int x, int y, int width, int height)
         { SetDimension(wxPoint(x, y), wxSize(width, height)); }