Merging r181368:
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r181368 | rsmith | 2013-05-07 14:53:22 -0700 (Tue, 07 May 2013) | 3 lines

Don't crash in IRGen if a conditional with 'throw' in one of its branches is
used as a branch condition.

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git-svn-id: https://llvm.org/svn/llvm-project/cfe/branches/release_33@181401 91177308-0d34-0410-b5e6-96231b3b80d8