Merging r369084:

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r369084 | ctopper | 2019-08-16 06:47:44 +0200 (Fri, 16 Aug 2019) | 5 lines

[X86] Manually reimplement getTargetInsertSubreg in X86DAGToDAGISel::matchBitExtract so we can call insertDAGNode on the target constant.

This is needed to maintain the topological sort order.

Fixes PR42992.
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llvm-svn: 369357