Merging r372675:

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r372675 | aemerson | 2019-09-23 17:09:23 -0700 (Mon, 23 Sep 2019) | 7 lines

[GlobalISel][IRTranslator] Fix switch table lowering to use signed LE not unsigned.

We were miscompiling switch value comparisons with the wrong signedness, which
shows up when we have things like switch case values with i1 types, which end up
being legalized incorrectly.

Fixes PR43383
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