Allow Names Changes on Unregistered Records

Allow Names Changes on Unregistered Records

Add Record names to be changed even on Records that aren't yet
registered.  We need to be able to do this for paste functionality
because we do not want to register def names before they are unique
and that can only happen once all paste operations are done.  This
change lets us update Record names formed by paste operations and
register the result later.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@142510 91177308-0d34-0410-b5e6-96231b3b80d8