Merging r199351:

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r199351 | aschwaighofer | 2014-01-15 23:53:18 -0500 (Wed, 15 Jan 2014) | 5 lines

BasicAA: We need to check both access sizes when comparing a gep and an
underlying object of unknown size.

Fixes PR18460.

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llvm-svn: 206053