libctf: fix libctf/testsuite/libctf-lookup/multidim-array on older arches

This patch inverts the ordering of nelems on multidimensional arrays on
versions of gcc without the CTF_F_ARRNELEMS flag. This allows those
systems which run older gcc to pass the test without modification to the
multidim-array.lk file.

libctf/ChangeLog:

	* testsuite/libctf-lookup/multidim-array.c: Test fixes.