Handle the invalid timestamp in zipfile

The month field is one based in the zipfile modification time. And
it causes an overflow converting it to struct tm. Switch to type to
signed integer to suppress the sub-overflow.

Bug: 153882979
Test: parse the problematic zipfile
Change-Id: Iaf47bcc7f83d61b18c9e7a98bb6ab3936c9257e3
2 files changed