Shared Memory
CSI 450 - HW#2

Modify the parent and child from last program to communicate results
via shared memory. In the first homework, the child could report the
results of the factorial to output, but the parent had no ability to
get the results. In this project, the parent will create some shared
memory (use ftok on the parent cpp file for both the parent and the
child to attach to the same shared memory segment). Then, it will
spawn the child which will compute the desired factorial and store the
result in shared memory. When the child is finished, the parent can
retrieve the result from shared memory and destroy the shared memory
segment. Use ipcs and ipcrm to appropriately determine if you are
using your shared memory segments appropriately.