VPP-98 Dedicated storage for VXLAN over IPv6 hash keys

VPP-98 Dedicated storage for VXLAN over IPv6 hash keys

When creating VXLAN over IPv6 the code was using storage for the
hash key that could later be moved. Since the key is larger than
the word size this was being referenced as a pointer; when the
storage moves that breaks the hash.

Instead allocate dedicated storage for the key.

This patch also includes other minor cleanups, including using
clib_memcpy in places it should be used and some whitespace
fixes.

Change-Id: I579f2cb515853ef56dedcca350fcad08aa6111a9
Signed-off-by: Chris Luke <chrisy@flirble.org>