Hello,

This patch adds the repoline patches (totally 17 of them) taken from the
'retpoline-20180107' branch at
``http://git.infradead.org/users/dwmw2/gcc-retpoline.git'' to gcc@7.

Last time it builds fine on my laptop. I am now re-building since I add
some comments on the patches. I will reply asap if anything goes wrong
with the re-build.