Update wxSpinCtrl size while changing the base under OSX

Changing the base changes the textual representation of the number
so we need to reset the best size of numeric box to enforce
size recalculation.

src/generic/spinctlg.cpp

@@ -639,6 +639,7 @@ bool wxSpinCtrl::SetBase(int base)
 
     m_base = base;
 
+    m_textCtrl->InvalidateBestSize();
     ResetTextValidator();
 
     // ... but DoValueToText() after doing it.