Update: improve FORCING memory allocation strategy macro handling

Update: improve FORCING memory allocation strategy macro handling

Do not alter the function disabling macros.
Allow for forcing secure or insecure on individual blocks of code by removing the function disabling macros.

The following should not be possible:
  int main(){
    normal_allocations();

    #define _f_memory_FORCE_secure_memory_
      secure_allocations();
    #undef _f_memory_FORCE_secure_memory_

    do_stuff();

    normal_deallocations();

    #define _f_memory_FORCE_secure_memory_
      secure_deallocations();
    #undef _f_memory_FORCE_secure_memory_

    return 0;
  }