README file stays intact.
I went ahead and left the README.md file deleted because it had broken git hashes. Better to use `git log -- lib/libc/glibc/` to find out the patches.
Upstream, some of the nonshared functions moved to be different for hurd and for linux. Since our glibc is linux-only we update to use the linux-specific files. This fixes std lib tests for x86_64 when linking glibc.