ls-files: use correct format string

ls-files: use correct format string

struct stat_data and struct cache_time both use unsigned ints for all
their members.  However the format string for 'git ls-files --debug'
currently uses %d for formatting these numbers.  This means that we
potentially print these values incorrectly if they are greater than
INT_MAX.

This has been the case since the --debug option was introduced in 'git
ls-files' in 8497421715 ("ls-files: learn a debugging dump format",
2010-07-31).

Signed-off-by: Thomas Gummerer <t.gummerer@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>