zdtm/ia32: print st_size as (long long)

Fixes compile-time errors on Fedora like:
In file included from unlink_fstat01.c:9:0:
> unlink_fstat01.c: In function ‘main’:
> ../lib/zdtmtst.h:123:11: error: format ‘%ld’ expects argument of type ‘long int’, but argument 4 has type ‘__off64_t {aka long long int}’ [-Werror=format=]
>   test_msg("FAIL: %s:%d: " format " (errno = %d (%s))\n", \

Signed-off-by: Dmitry Safonov <dsafonov@virtuozzo.com>
Signed-off-by: Andrei Vagin <avagin@virtuozzo.com>