strace: handle possible NULL from localtime() call

strace: handle possible NULL from localtime() call

* strace.c (printleader): Print raw tv_sec value if localtime() returned
NULL.
* tests/localtime.c: New file.
* tests/localtime.test: New test.
* tests/Makefile.am (check_PROGRAMS): Add localtime.
(MISC_TESTS): Add localtime.test.
(localtime_LDADD): New variable.
* tests/.gitignore: Add localtime.
* ci/install-dependencies.sh (common_packages): Add faketime.

Co-Authored-by: Dmitry V. Levin <ldv@altlinux.org>
Closes: https://github.com/strace/strace/issues/42