ia64: restore symbol versions for symbols defined in assembly

The ia64 build generates many warnings like this:

   WARNING: EXPORT symbol "empty_zero_page" [vmlinux] version generation failed, symbol will not be versioned.

Besides adding the necessary header this also requires fiddling with
some explicit .S -> .o rules.

Cc: IA64-ML <linux-ia64@vger.kernel.org>
Signed-off-by: Jan Beulich <jbeulich@suse.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>