The previous value, 0x8000, caused problems.

The minimum value required for relocatable images to load (starting from NULL)
is 0x13000. For additional buffer, the temporary hack here is to increase
that said value.

Will be utilized later.

- Introduce end_address_upper_bound.
- Add mask.
  - Some additional investigation and testing is necessary.
  - Right now, it feels like the mask just works because of a magic
    spell called "Works on my machine.". I didn't get creative with
    the spell name (which does not exist), because I don't know how
    spells sound like. Sorrry.
- Some architecture-specific work may be needed.
- Some fine-tuning and debugging information for ASLR is necessary.

- 0xFFFFF0 cut off the upper 4 bits.

- Some sleep is required.
- Some bitwise arithmetic was avoided.
- Why over-engineer a literal mask value?
- I should take a break.

There is something wrong going on here in this current revision.
Not sure why.

- It's #[cfg(not(feature = aslr))], not #[not(cfg(feature = aslr))].
- Some additional typo-induced bug was fixed.

.-.

We should probably tell Uhyve that it is enabled once we are sure that nothing
has gone wrong. What we should do when something goes wrong (can anything go
wrong?) is an open question.