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

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

This patch eliminates another way in which ex-ports and non-ex-ports
architectures differ, by moving architecture-specific entries from the
top-level shlib-versions file and that in nptl/ to appropriate sysdeps
directories.  As with my previous patch
<https://sourceware.org/ml/libc-alpha/2014-06/msg00949.html>, I do not
change the regular expressions used; even where the present
expressions seem more general, I believe they are in fact specific to
the chosen sysdeps directory, because any port that matches the
expression but not the sysdeps directory does not currently exist, and
so would use different symbol versions if added in future (and an
intended goal of these changes is to eliminate the first column in
shlib-versions completely rather than having two different mechanisms
in use for system-specific configuration).

Tested on x86_64 that this does not change the installed shared
libraries.  (x86_64 of course does not provide much test coverage for
this patch - what should be architecture-specific contents in
shlib-versions for x86_64 is currently abi-*-ld-soname Makefile
settings, until gnu/lib-names.h is generated more like gnu/stubs.h so
those can move back to shlib-versions.)

	* nptl/shlib-versions: Remove architecture-specific entries.
	Moved to files in sysdeps.
	* shlib-versions: Likewise.
	* sysdeps/unix/sysv/linux/powerpc/powerpc64/shlib-versions: New
	file.
	* sysdeps/unix/sysv/linux/s390/s390-64/shlib-versions: Likewise.
	* sysdeps/unix/sysv/linux/sh/shlib-versions: Likewise.
	* sysdeps/unix/sysv/linux/sparc/sparc32/shlib-versions: Likewise.
	* sysdeps/unix/sysv/linux/sparc/sparc64/shlib-versions: Likewise.