[Google] Port patch r215585 to Google/4.9 branch

[Carrot Wei]

Hi

In Google application we hit the same problem as
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63341, so we also need
the patch r215585 for Google/4.9 branch.

It passed following tests:
bootstrap and regression test on x86-64.
regression test on ppc.

Google reference 18687126.

OK for Google/4.9 branch?

patch
Description: Binary data