fix some bugs (found by inspection) where LICM would not update

fix some bugs (found by inspection) where LICM would not update
LICM correctly.  When sinking an instruction, it should not add
entries for the sunk instruction to the AST, it should remove
the entry for the sunk instruction.  The blocks being sunk to
are not in the loop, so their instructions shouldn't be in the
AST (yet)!

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@112447 91177308-0d34-0410-b5e6-96231b3b80d8