Clean up gnu/lib-names.h generation (bug 14171).

Clean up gnu/lib-names.h generation (bug 14171).

This patch eliminates the mixture of SONAME information in
shlib-versions files and SONAME information used to generate
gnu/lib-names.h in makefiles, with the information in the makefiles
being removed so all this information comes from the shlib-versions
files.

So that gnu/lib-names.h supports multiple ABIs, it is changed to be
generated on the same basis as gnu/stubs.h: when there are multiple
ABIs, gnu/lib-names.h is a wrapper header (the same header installed
whatever ABI is being built) and separate headers such as
gnu/lib-names-64.h contain the substantive contents (only one such
header being installed by any glibc build).

The rules for building gnu/lib-names.h were moved from Makeconfig to
Makerules because they need to come after sysdeps makefiles are
included (now that "ifndef abi-variants" is a toplevel conditional on
the rules rather than $(abi-variants) being evaluated later inside the
commands for a rule).

Tested for x86_64 and x86 that the installed shared libraries are
unchanged by this patch, and examined the installed gnu/lib-names*.h
headers by hand.  Also tested the case of a single ABI (where there is
just a single header installed, again like stubs.h) by hacking
abi-variants to empty for x86_64.

	[BZ #14171]
	* Makeconfig [$(build-shared) = yes]
	($(common-objpfx)soversions.mk): Don't handle SONAMEs specified in
	makefiles.
	[$(build-shared) = yes && $(soversions.mk-done) = t]
	($(common-objpfx)gnu/lib-names.h): Remove rule.
	[$(build-shared) = yes && $(soversions.mk-done) = t]
	($(common-objpfx)gnu/lib-names.stmp): Likewise.  Split and moved
	to Makerules.
	[$(build-shared) = yes && $(soversions.mk-done) = t]
	(before-compile): Don't append $(common-objpfx)gnu/lib-names.h
	here.
	[$(build-shared) = yes && $(soversions.mk-done) = t]
	(common-generated): Don't append gnu/lib-names.h and
	gnu/lib-names.stmp here.
	* Makerules [$(build-shared) = yes && $(soversions.mk-done) = t]
	(lib-names-h-abi): New variable.
	[$(build-shared) = yes && $(soversions.mk-done) = t]
	(lib-names-stmp-abi): Likewise.
	[$(build-shared) = yes && $(soversions.mk-done) = t &&
	abi-variants] (before-compile): Append
	$(common-objpfx)$(lib-names-h-abi).
	[$(build-shared) = yes && $(soversions.mk-done) = t &&
	abi-variants] (common-generated): Append gnu/lib-names.h.
	[$(build-shared) = yes && $(soversions.mk-done) = t &&
	abi-variants] (install-others-nosubdir): Depend on
	$(inst_includedir)/$(lib-names-h-abi).
	[$(build-shared) = yes && $(soversions.mk-done) = t &&
	abi-variants] ($(common-objpfx)gnu/lib-names.h): New rule.
	[$(build-shared) = yes && $(soversions.mk-done) = t]
	($(common-objpfx)$(lib-names-h-abi)): New rule.
	[$(build-shared) = yes && $(soversions.mk-done) = t]
	($(common-objpfx)$(lib-names-stmp-abi)): Likewise.
	[$(build-shared) = yes && $(soversions.mk-done) = t]
	(common-generated): Append $(lib-names-h-abi) and
	$(lib-names-stmp-abi).
	* scripts/lib-names.awk: Do not handle multi being set.
	* sysdeps/unix/sysv/linux/aarch64/Makefile (abi-lp64-ld-soname):
	Remove variable.
	(abi-lp64_be-ld-soname): Likewise.
	* sysdeps/unix/sysv/linux/arm/Makefile (abi-soft-ld-soname):
	Likewise.
	(abi-hard-ld-soname): Likewise.
	* sysdeps/unix/sysv/linux/i386/shlib-versions: New file.
	* sysdeps/unix/sysv/linux/mips/Makefile (abi-o32_soft-ld-soname):
	Remove variable.
	(abi-o32_hard-ld-soname): Likewise.
	(abi-o32_soft_2008-ld-soname): Likewise.
	(abi-o32_hard_2008-ld-soname): Likewise.
	(abi-n32_soft-ld-soname): Likewise.
	(abi-n32_hard-ld-soname): Likewise.
	(abi-n32_soft_2008-ld-soname): Likewise.
	(abi-n32_hard_2008-ld-soname): Likewise.
	(abi-n64_soft-ld-soname): Likewise.
	(abi-n64_hard-ld-soname): Likewise.
	(abi-n64_soft_2008-ld-soname): Likewise.
	(abi-n64_hard_2008-ld-soname): Likewise.
	* sysdeps/unix/sysv/linux/powerpc/Makefile (abi-64-v1-ld-soname):
	Likewise.
	(abi-64-v2-ld-soname): Likewise.
	* sysdeps/unix/sysv/linux/powerpc/powerpc64/shlib-versions: Add
	ld.so entries.
	* sysdeps/unix/sysv/linux/s390/Makefile (abi-64-ld-soname): Remove
	variable.
	* sysdeps/unix/sysv/linux/s390/s390-64/shlib-versions: Add ld.so
	entry.
	* sysdeps/unix/sysv/linux/x86/Makefile (abi-32-ld-soname): Remove
	variable.
	(abi-64-ld-soname): Likewise.
	(abi-x32-ld-soname): Likewise.
	* sysdeps/unix/sysv/linux/x86_64/64/shlib-versions: Add ld.so
	entry.
	* sysdeps/unix/sysv/linux/x86_64/x32/shlib-versions: Likewise.