Move OS-specific shlib-versions entries to sysdeps files.

Move OS-specific shlib-versions entries to sysdeps files.

This patch moves OS-specific entries in the top-level shlib-versions
file to appropriate sysdeps directories.  I left the entries in
nptl/shlib-versions and nptl_db/shlib-versions unchanged; I think it
can be for those doing non-Linux NPTL-using ports to figure out
whether those entries should actually be OS-independent or should move
to sysdeps.

Given these two patches, I think the only further change needed before
the first column of shlib-versions can be eliminated will be changing
sysdeps/unix/sysv/linux/powerpc/powerpc64/shlib-versions to use %ifdef
to distinguish BE and LE configurations, instead of relying on the
powerpc64-.*-linux.* and powerpc.*le-.*-linux.* patterns.

Tested on x86_64 that the installed shared libraries are unchanged by
this patch.

	* shlib-versions: Remove OS-specific entries.  Moved to files in
	sysdeps.
	* sysdeps/mach/hurd/shlib-versions: New file.
	* sysdeps/unix/sysv/linux/shlib-versions: Likewise.