m68k: Remove vDSO support

m68k: Remove vDSO support

Although defined in initial TLS/NPTL ABI for m68k and ColdFire [1], kernel
support was never pushed upstream.  This patch removes the unused m68k
vDSO support.

Checked with a build against m68k and m68k-coldfire and some basic
tests on ARAnyM.

	* sysdeps/unix/sysv/linux/m68k/Makefile (sysdep_routines,
	sysdep-rtld-routines): Remove rules.
	* sysdeps/unix/sysv/linux/m68k/Versions (libc) [GLIBC_PRIVATE]:
	Remove __vdso_atomic_cmpxchg_32 and __vdso_atomic_barrier.
	(ld) [GLIBC_PRIVATE]: __rtld___vdso_read_tp,
	__rtld___vdso_atomic_cmpxchg_32, and __rtld___vdso_atomic_barrier.
	* sysdeps/unix/sysv/linux/m68k/coldfire/atomic-machine.h
	(atomic_compare_and_exchange_val_acq, atomic_full_barrier): Remove
	vDSO path for SHARED.
	* sysdeps/unix/sysv/linux/m68k/init-first.c: Remove file.
	* sysdeps/unix/sysv/linux/m68k/libc-m68k-vdso.c: Likewise.
	* sysdeps/unix/sysv/linux/m68k/m68k-helpers.S: Likewise.
	* sysdeps/unix/sysv/linux/m68k/m68k-vdso.c: Likewise.
	* sysdeps/unix/sysv/linux/m68k/m68k-vdso.h: Likewise.
	* sysdeps/unix/sysv/linux/m68k/m68k-helpers.c: New file.

[1] https://lists.debian.org/debian-68k/2007/11/msg00071.html