Fix directory traversal and permission race security vulnerabilities in
gzip, and zgrep improper argument sanitation.

Security: CAN-2005-0758, CAN-2005-0988, CAN-2005-1228
Security: FreeBSD-SA-05:11.gzip
Obtained from: RedHat, Steve Grubb via RedHat, Debian
Approved by: maintainer timeout (4 days; security)