Merging r368230:

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r368230 | akhuang | 2019-08-08 00:49:40 +0200 (Thu, 08 Aug 2019) | 2 lines

Recommit "[MS] Emit S_HEAPALLOCSITE debug info in Selection DAG"
with a fix to clear the SDNode map when SelectionDAG is cleared.
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llvm-svn: 368571