vm: reset the last encountered label id, to allow back and forth
vm: reset the last encountered label id, to allow back and forth

The label ids are strictly ordered and the vm keeps track of those ids
for determining in which direction the next label id could be found
(little optimization, in the future, a direct relative offset will be
used of course)

nany-lang/nanyc,nany-lang/nanyc,nany-lang/nanyc,milipili/nany,nany-lang/nany,nany-lang/nany,milipili/nany,nany-lang/nany,milipili/nany