Prefix all the vxlan ifconfig commands so they are unique

And rehook ifvxlan back into the build.
MFV r275844:

Fix unbound remote denial of service vulnerability.

Security:	FreeBSD-SA-14:30.unbound
Security:	CVE-2014-8602
Adjust printf format specifiers for dev_t and ino_t in user space.

ino_t and dev_t are about to become uint64_t.

Reviewed by:	kib, mckusick
Adjust printf format specifiers for dev_t and ino_t in kernel.

ino_t and dev_t are about to become uint64_t.

Reviewed by:	kib, mckusick
Initilize the msg_flags field consistently in all code paths.

Reported by:	Coverity
CID:		1018726
Use memory regions information provided in FDT.

Reviewed by:	brooks
Sponsored by:	DARPA, AFRL
o Add PIO[2,3] devices information
o Enable Virtio Block