1. It now actually uses tarjan's algorithm, so it is a efficient inverse
ackerman's function for union operations, not linear time.
2. It now stores one copy of the data in the set instead of two.
3. It now works for elements other than pointers.
4. It now has a more STL-like interface that exposes iterators instead
of internal implementation details.
llvm-svn: 20677
Move include/Config and include/Support into include/llvm/Config,
include/llvm/ADT and include/llvm/Support. From here on out, all LLVM
public header files must be under include/llvm/.
llvm-svn: 16137
