fixed EXT-4529 [BSI] X in tabbed Instant Message functions as a minimize -

--HG--
branch : product-engine

indra/newview/skins/default/xui/en/floater_im_container.xml

 <?xml version="1.0" encoding="utf-8" standalone="yes" ?>
 <multi_floater
- can_minimize="false"
+ can_close="false"  
+ can_minimize="true"
  can_resize="true"
  height="390"
  layout="topleft"