[travis] Ensure that most recent tag is always available
Remove clone depth limit, to ensure that the most recent tag (from
which the version should be constructed) is always present.
Signed-off-by: Michael Brown <mcb30@ipxe.org>
Allow for automated builds via Travis CI (https://travis-ci.org).
Note that the bin-i386-linux build platform is deliberately omitted
since the required linux-libc-dev:i386 package is not on the allowed
packages list for the Travis 14.04 ("trusty") container environment.
Signed-off-by: Michael Brown <mcb30@ipxe.org>