don't OR integer error values together as this does not make sense.
Instead bail on the first failed command.
Provide -o vers= support for mount_nfs.

Our mount_nfs does use -o nfsv<2|3|4> or -2 or -3 to specify the version.
OSX (these days), Solaris, and Linux use -o vers=<2,3,4>.

With the upcoming autofs support we can make a lot of (entrerprisy) setups
getting mount options from LDAP just work by providing -o vers= compatibility.

PR:		192379
Reviewed by:	wblock, bjk (man page), rmacklem, emaste
MFC after:	3 days
Sponsored by:	DARPA,AFRL
Add support for Huawei E3272 modems which are supported by the CDC
ethernet class.

Note: This is untested as I do not have a device like this. That is
reflected in the MFC timeout.

PR:		192345
Submitted by:	rozhuk.im gmail.com
MFC after:	4 weeks