tests: use tail_alloc instead of calloc in bpf-obj_get_info_by_fd-prog*

tests: use tail_alloc instead of calloc in bpf-obj_get_info_by_fd-prog*

This guarantees that map_info and prog_info objects are not accessed
out of bounds.

* tests/bpf-obj_get_info_by_fd.c: Include <string.h>.
(main): Use tail_alloc instead of calloc for map_info and prog_info.