src/ia64/unix.S: unbreak small struct handling

src/ia64/unix.S: unbreak small struct handling

commit 6e8a4460833594d5af1b4539178025da0077df19
added FFI_TYPE_COMPLEX value type (comes after FFI_TYPE_POINTER)

ia64 ffi_closure_unix reiles on the ordering of
FFI_ enums as ia64 has ia64-specific FFI types:
small struct and FPU extesions.

As a result all tests handling small structs broke.

The change fixes dispatch table by adding (no-op)
FFI_TYPE_COMPLEX entry
This has positive effect of unbreaking most tests
on ia64:

                 === libffi Summary ===

-# of expected passes            1595
-# of unexpected failures        295
+# of expected passes            1930
+# of unexpected failures        10
 # of unsupported tests          30

Signed-off-by: Sergei Trofimovich <slyfox@gentoo.org>