Merging r338749:

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r338749 | mstorsjo | 2018-08-02 20:12:08 +0200 (Thu, 02 Aug 2018) | 6 lines

Work around more GCC miscompiles exposed by r338464.

This is the same fix as in r338478, for another occurrance of the
same pattern from r338464.

See gcc.gnu.org/PR86769 for details of the bug.
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git-svn-id: https://llvm.org/svn/llvm-project/cfe/branches/release_70@338845 91177308-0d34-0410-b5e6-96231b3b80d8