Revert "crtools: close all desriptors only for the root task"

We have a race. Consider we have 3 tasks, A, B and C. A and B
share fdtable, C -- does not. Then we might be in a situation
when A is restoring memory reading mem images, and B -- forking
the C child. In that case descriptors held by A (for mem restore)
will be inherited by C and will not get closed.

This reverts commit d36e07aabe073993d8ae9695e33f6e45b2eb6a21.