x86, vdso: Finish removing VDSO32_PRELINK

It's a declaration of a nonexistent symbol.  We can get rid of the
64-bit versions, too, but that's more intrusive.

Signed-off-by: Andy Lutomirski <luto@amacapital.net>
Cc: Stefani Seibold <stefani@seibold.net>
Link: http://lkml.kernel.org/r/2ce2ce18447d8a0b78d44a278a066b6c0af06b32.1395366931.git.luto@amacapital.net


Signed-off-by: H. Peter Anvin <hpa@zytor.com>