Declare exit_calcurse() "noreturn".
Declare exit_calcurse() "noreturn".

Functions that never return should be declared "noreturn" to tell the
compiler this fact. Also, clang-analyzer will detect this attribute and
take it into account when running scan-build.

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

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