Revert commit 66140 since it caused several failures

in the Ada testcase.  Reverting this only covers up
the real problem, which is a nasty conceptual difficulty
in the phi elimination pass: when eliminating phi nodes
in landing pads, the register copies need to come before
the invoke, not at the end of the basic block which is
too late...  See PR3784.

llvm-svn: 66826