Merging r371969:

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r371969 | karka | 2019-09-16 11:52:23 +0200 (Mon, 16 Sep 2019) | 13 lines

Change signature of __builtin_rotateright64 back to unsigned

The signature of __builtin_rotateright64 was by misstake changed from
unsigned to signed in r360863, this patch will change it back to
unsigned as intended.

This fixes pr43309

Reviewers: efriedma, hans

Reviewed By: hans

Differential Revision: https://reviews.llvm.org/D67606
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llvm-svn: 372100