it couldn't find the class on first try. This fixes the problems mentioned
by Shinta as part of bug #2086.
* Got rid of GetNumber() - there is a POSIX function strtoul() for exactly
this purpose.
* demangle_class_name() can now fail.
git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@25179 a95241bf-73f2-0310-859d-f6bbb57e9c96