pkg/system: fix cleanup in tests

Docker-DCO-1.1-Signed-off-by: Cristian Staretu <cristian.staretu@gmail.com> (github: unclejack)
pkg/archive: fix TempArchive cleanup w/ one read

This fixes the removal of TempArchives which can read with only one
read. Such archives weren't getting removed because EOF wasn't being
triggered.

Docker-DCO-1.1-Signed-off-by: Cristian Staretu <cristian.staretu@gmail.com> (github: unclejack)
pkg/symlink: fix cleanup for tests

Docker-DCO-1.1-Signed-off-by: Cristian Staretu <cristian.staretu@gmail.com> (github: unclejack)
integ-cli: fix cleanup in test which mounts tmpfs

Docker-DCO-1.1-Signed-off-by: Cristian Staretu <cristian.staretu@gmail.com> (github: unclejack)
integ-cli: fix cleanup in build tests

Docker-DCO-1.1-Signed-off-by: Cristian Staretu <cristian.staretu@gmail.com> (github: unclejack)
graphdriver/aufs: fix tmp cleanup in tests

Docker-DCO-1.1-Signed-off-by: Cristian Staretu <cristian.staretu@gmail.com> (github: unclejack)
Merge pull request #9261 from unclejack/fix_test_tmp_cleanup

fix cleanup of /tmp in tests