netlink

By default ueventd creates device nodes under /dev based on the ueventd
DEVPATH.  Several subsystems have special rules which are hardcoded in
devices.c.  Moving forward these special rules should go in ueventd.rc.

Special rules have the syntax:

	subsystem <s>
		devname (uevent_devname|uevent_devpath)
		[dirname <dir>]

Devices matching SUBSYSTEM=<s> will be populated under <dir>.  dirname
is optional and defaults to /dev.  If dirname is provided, <dir> must
start with "/".

If devname is uevent_devname, ueventd will create the device node as
<dir>/DEVNAME.  DEVNAME may include intermediate subdirectories, which
ueventd will automatically create.

If devname is uevent_devpath, ueventd will use the legacy behavior of
computing DEVPATH_BASE=basepath(DEVPATH), and creating the device node
as <dir>/DEVPATH_BASE.

The new parsing code is based on init_parser.c, with small tweaks to
handle commands which don't fall under a section header.

Change-Id: I3bd1b59d7e62dfc9d289cf6ae889e237fb5bd7c5
Signed-off-by: Greg Hackmann <ghackmann@google.com>