Remove the explicit SDNodeIterator::operator= in favor of the implicit default

There doesn't seem to be any need to assert that iterator assignment is
between iterators over the same node - if you want to reuse an iterator
variable to iterate another node, that's perfectly acceptable. Just
don't mix comparisons between iterators into disjoint sequences, as
usual.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@231135 91177308-0d34-0410-b5e6-96231b3b80d8

lib/CodeGen/LiveInterval.cpp

@@ -743,7 +743,6 @@ void LiveRange::flushSegmentSet() {
       segments.empty() &&
       "segment set can be used only initially before switching to the array");
   segments.append(segmentSet->begin(), segmentSet->end());
-  delete segmentSet;
   segmentSet = nullptr;
   verify();
 }