Merging r197089:

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r197089 | hfinkel | 2013-12-11 15:12:25 -0800 (Wed, 11 Dec 2013) | 6 lines

Fix the PPC subsumes-predicate check

For one predicate to subsume another, they must both check the same condition
register. Failure to check this prerequisite was causing miscompiles.

Fixes PR18003.
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llvm-svn: 197126