tests/tcg/multiarch: fix 32bit linux-test on 64bit host

tests/tcg/multiarch: fix 32bit linux-test on 64bit host

Fix:

  TEST    linux-test on i386
  .../tests/tcg/multiarch/linux-test.c:201: readdir

readdir() calls getdents64() to have the list of the entries in a
directory, and getdents64() can return 64bit d_off values (with ext4,
for instance) that will not fit in the 32bit d_off field of the
readdir() dirent structure.

To avoid that, use readdir64() to use a 64bit d_off field too.

Signed-off-by: Laurent Vivier <laurent@vivier.eu>
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>