Prevent LiveRangeEdit from deleting bundled instructions.

We have no targets on trunk that bundle before regalloc. However, we
have been advertising regalloc as bundle safe for use with out-of-tree
targets. We need to at least contain the parts of the code that are
still unsafe.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@184620 91177308-0d34-0410-b5e6-96231b3b80d8