* Finish the implementation of isEdgeFeasible this fixes bug:

    test/Regression/Transforms/SCCP/2002-05-02-EdgeFailure.ll
* SCCP now preserves the CFG:  It leaves conditional branches the way they
  are in the program, not simplifying them.  A seperate pass should eliminate
  the potentially dead basic blocks and edges in the CFG.

llvm-svn: 2446