Fix a gcc warning introduced by the previous commit

Reverting the commits broke indentation, which resulted in
-Wmisleading-indentation from (recent) gcc, so fix it by indenting the
restored "if" properly.

See #13130.

src/msw/anybutton.cpp

@@ -590,8 +590,8 @@ wxSize wxAnyButton::DoGetBestSize() const
         if ( ::SendMessage(GetHwnd(), BCM_GETIDEALSIZE, 0, (LPARAM)&idealSize) )
             size.Set(idealSize.cx, idealSize.cy);
 
-            if ( m_imageData )
-                AdjustForBitmapMargins(size);
+        if ( m_imageData )
+            AdjustForBitmapMargins(size);
     }
 
     // If we failed to set the size using BCM_GETIDEALSIZE above, determine it