Bring the fixes mentioned below from upstream to our gcc-5.2 powerpc64-gcc
port.

[1]: https://gcc.gnu.org/ml/gcc-patches/2015-12/msg02057.html
[2]: https://gcc.gnu.org/ml/gcc-patches/2015-12/msg00685.html

PR: 205394, 205440
Approved by: bapt (maintainer)