tests/tests1: fix printf format for size_t arguments

tests/tests1: fix printf format for size_t arguments

Change %d to %llu and add cast to unsigned long long for size_t arguments,
otherwise compilation will fail with errors like:

test1.c:70:15: error: format ‘%d’ expects argument of type ‘int’, but argument 2 has type ‘size_t {aka long unsigned int}’ [-Werror=format=]

%zu is avoided to stay compatible with old libc versions (like old Visual
Studio).