vlog: Fix "/dev/log" test
commit
7905aae3fc1633c2c44c8fdb9e9d3a3d6e63439b
("vlog: Don't fail syslog initialization in chroot.")
uses os.path.isfile("/dev/log"), which tests if the given path
is a regular file, to see if syslog can be usable.
However, /dev/log is not a regular file for platforms I looked at.
* On Ubuntu 14.04 and CentOS 6.5, /dev/log is a socket
* On NetBSD-6, /dev/log is a symlink to a socket
Replace the test with os.path.exists() so that it can work
as intended for these platforms.
Signed-off-by: YAMAMOTO Takashi <yamamoto@valinux.co.jp>
Acked-by: Gurucharan Shetty <gshetty@nicira.com>