Remove PREPARE_VERSION and PREPARE_VERSION_KNOW

This patch removes the PREPARE_VERSION and PREPARE_VERSION_KNOW macro
and uses a static inline function instead, get_vdso_symbol.  Each
architecture that supports vDSO must define the Linux version and its
hash for symbol resolution (VDSO_NAME and VDSO_HASH macro respectively).

It also organizes the HAVE_*_VSYSCALL for mips, powerpc, and s390 to
define them on a common header.

The idea is to require less code to configure and enable vDSO support
for newer ports.  No semantic changes are expected.

Checked with a build against all affected architectures.

	* sysdeps/unix/make-syscalls.sh: Make vDSO call use get_vdso_symbol.
	* sysdeps/unix/sysv/linux/aarch64/gettimeofday.c (__gettimeofday):
	Use get_vdso_symbol instead of _dl_vdso_vsym.
	* sysdeps/unix/sysv/linux/powerpc/time.c (time): Likewise.
	* sysdeps/unix/sysv/linux/riscv/flush-icache.c
	(__lookup_riscv_flush_icache): Likewise.
	* sysdeps/unix/sysv/linux/x86/gettimeofday.c (__gettimeofday):
	Likewise.
	* sysdeps/unix/sysv/linux/x86/time.c (time): Likewise.
	* sysdeps/unix/sysv/linux/powerpc/gettimeofday.c: Likewise.
	* sysdeps/unix/sysv/linux/aarch64/init-first.c: Likewise.
	* sysdeps/unix/sysv/linux/arm/init-first.c: Likewise.
	* sysdeps/unix/sysv/linux/i386/init-first.c: Likewise.
	* sysdeps/unix/sysv/linux/mips/init-first.c: Likewise.
	* sysdeps/unix/sysv/linux/powerpc/init-first.c: Likewise.
	* sysdeps/unix/sysv/linux/riscv/init-first.c: Likewise.
	* sysdeps/unix/sysv/linux/sparc/init-first.c: Likewise.
	* sysdeps/unix/sysv/linux/s390/init-first.c: Likewise.
	* sysdeps/unix/sysv/linux/x86_64/init-first.c: Likewise.
	* sysdeps/unix/sysv/linux/aarch64/sysdep.h (VDSO_NAME, VDSO_HASH):
	Define.
	* sysdeps/unix/sysv/linux/arm/sysdep.h (VDSO_NAME, VDSO_HASH):
	Likewise.
	* sysdeps/unix/sysv/linux/i386/sysdep.h (VDSO_NAME, VDSO_HASH):
	Likewise.
	* sysdeps/unix/sysv/linux/riscv/sysdep.h (VDSO_NAME, VDSO_HASH):
	Likewise.
	* sysdeps/unix/sysv/linux/sparc/sysdep.h (VDSO_NAME, VDSO_HASH):
	Likewise.
	* sysdeps/unix/sysv/linux/x86_64/sysdep.h (VDSO_NAME, VDSO_HASH):
	Likewise.
	* sysdeps/unix/sysv/linux/mips/mips32/sysdep.h
	(HAVE_CLOCK_GETTIME_VSYSCALL, HAVE_GETTIMEOFDAY_VSYSCALL): Remove
	definition.
	* sysdeps/unix/sysv/linux/mips/mips64/n32/sysdep.h
	(HAVE_CLOCK_GETTIME_VSYSCALL, HAVE_GETTIMEOFDAY_VSYSCALL): Likewise.
	* sysdeps/unix/sysv/linux/mips/mips64/n64/sysdep.h
	(HAVE_CLOCK_GETTIME_VSYSCALL, HAVE_GETTIMEOFDAY_VSYSCALL): Likewise.
	* sysdeps/unix/sysv/linux/powerpc/powerpc32/sysdep.h
	(HAVE_CLOCK_GETTIME_VSYSCALL, HAVE_GETTIMEOFDAY_VSYSCALL): Likewise.
	* sysdeps/unix/sysv/linux/powerpc/powerpc64/sysdep.h
	(HAVE_CLOCK_GETTIME_VSYSCALL, HAVE_GETTIMEOFDAY_VSYSCALL): Likewise.
	* sysdeps/unix/sysv/linux/s390/s390-32/sysdep.h
	(HAVE_CLOCK_GETRES_VSYSCALL, HAVE_CLOCK_GETTIME_VSYSCALL,
	HAVE_GETTIMEOFDAY_VSYSCALL, HAVE_GETCPU_VSYSCALL): Likewise.
	* sysdeps/unix/sysv/linux/s390/s390-64/sysdep.h
	(HAVE_CLOCK_GETRES_VSYSCALL, HAVE_CLOCK_GETTIME_VSYSCALL,
	HAVE_GETTIMEOFDAY_VSYSCALL, HAVE_GETCPU_VSYSCALL): Likewise.
	* sysdeps/unix/sysv/linux/mips/sysdep.h: New file.
	* sysdeps/unix/sysv/linux/powerpc/sysdep.h: Likewise.
	* sysdeps/unix/sysv/linux/s390/sysdep.h: Likewise.
	* sysdeps/unix/sysv/linux/dl-vdso.h (PREPARE_VERSION,
	PREPARE_VERSION_KNOWN, VDSO_NAME_LINUX_2_6, VDSO_HASH_LINUX_2_6,
	VDSO_NAME_LINUX_2_6_15, VDSO_HASH_LINUX_2_6_15,
	VDSO_NAME_LINUX_2_6_29, VDSO_HASH_LINUX_2_6_29,
	VDSO_NAME_LINUX_4_15, VDSO_HASH_LINUX_4_15): Remove defines.
	(get_vdso_symbol): New function.