Large -K is not respected

[mrvollger]

Hi,

This is basically a duplicate/reminder of lh3/minimap2#491 but for yak. In short if -K is too large it only processes one sequence at a time.

Will process many at once:

 ./yak count -K 2000000000  mat_ill.fasta -o  /dev/null

Will only process one at a time:

 ./yak count -K 20000000000  mat_ill.fasta -o  /dev/null

Best,
Mitchell