src/llist.c: Use stable insertion algorithm
src/llist.c: Use stable insertion algorithm

Ensure the relative order of elements with equal keys is maintained when
inserting into a sorted list.

Signed-off-by: Lukas Fleischer <af90e31281d8305af43dc616c5aaca3c7165f8a7@cryptocrack.de>

lfos/calcurse,lfos/calcurse,dunecn/calcurse,lfos/calcurse,dunecn/calcurse