Update to 3.0-2440-gf6f4014f

• jail -x: Add back a default for NXBDESTDIR for older base branches
• testport/bulk -i: Fix not installing main package in jail.
• bulk: Store build name in PACKAGES/.buildname
• jail -cu -m ftp: Fix freebsd-update not being properly ran.
• HTML: Don't show NaN:NaN:NaN for duration on older builds.
• HTML Remaining: Hide table if there's no [more] data.
• HTML Remaining: Hide find warnings from racing with clean.sh.
• pkgclean: Remove packages from .building directory if it exists.
• jail -u -m ftp: Don't run freebsd-update on unsupported branches.