display the shield class number unconditionally, so that if you only have a magical shield, you can see the shield class properly.
git-svn-id: https://crawl-ref.svn.sourceforge.net/svnroot/crawl-ref/trunk@4430 c06c8d41-db1a-0410-9941-cceddc491573
4RMDJ2EE4TFOQPO27F4XKZNUWMXINHZCC2566IXYXMRDK24ZLIIAC