well, as the pretty explanatory error explains, you are missing a library, or its in a place where Globulation cant find it. First you should try 'locate'ing the file (locate libstdc++.so) or if you dont have locate: find / -name "libstdc++.so*"
If you do find it that way, just cp it under /usr/lib/ and youre all set.
I have seveeral occurances of it in my system even though it doesnt belong to any slackware package, so I actually have no idea where it has come from, but by all means you should have it. (Dont quote me for that, Suse is famous for weirdnesses)