False unsolvable boards using the C solver

[marccane]

I'm attaching two solvable boards that are reported unsolvable by the C solver with default parameters

% flow_solver -q *
levelpack_2_13x13_24.txt u        1.464       193471
levelpack_16_12x12_3.txt u        0.139        15292


                 2 total u        1.603       208763

levelpack_2_13x13_24.txt
levelpack_16_12x12_3.txt

I found out that when you add the -O parameter (Disable outside-in searching) both get solved correctly

levelpack_2_13x13_24

levelpack_16_12x12_3