InstCombine: Remove ilist iterator implicit conversions, NFC

Stop relying on implicit conversions of ilist iterators in
LLVMInstCombine.  No functionality change intended.

llvm-svn: 250183
diff --git a/llvm/lib/Transforms/InstCombine/InstCombineInternal.h b/llvm/lib/Transforms/InstCombine/InstCombineInternal.h
index 79cb5f2..1bb3ad6 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineInternal.h
+++ b/llvm/lib/Transforms/InstCombine/InstCombineInternal.h
@@ -400,7 +400,7 @@
     assert(New && !New->getParent() &&
            "New instruction already inserted into a basic block!");
     BasicBlock *BB = Old.getParent();
-    BB->getInstList().insert(&Old, New); // Insert inst
+    BB->getInstList().insert(Old.getIterator(), New); // Insert inst
     Worklist.Add(New);
     return New;
   }