x86 cleanups from the LTO tree

Andi Kleen
2017-12-22T00:28:07Z

These are all the fixes for the x86 tree needed for LTO. They are strictly
not needed without LTO, but I believe they can be all considered cleanups
and documentation improvements and are valuable because of that.

The initconst/data fixes help generating correct section permissions in the
vmlinux ELF file.