Works around govix issue loading libvix

Right now, there is no way to statically compile libvix, it is a VMware
issue rather than Go's. This change attempts to lay out the work
required to get a portable VIX provider working and sets a temporary
path for development work.

A strategy to avoid setting LD_LIBRARY_PATH is setting a rpath with
$ORIGIN inside the binary, but it did not work for Clang in OSX. Also, Clang
embeds an absolute path which is undesired. There are some outstanding
issues in Go that could aid this, more specifically:
https://code.google.com/p/go/issues/detail?id=7891