We don't have it mapped in our memory map, so this can actually crash
checked reads like Read_U32.
Since it isn't mapped, and it can't possibly be valid in retail PSP
games to access VRAM this way, I don't think this will cause any
problems.
However, if it does, we'll have to add the corresponding mappings to the
memory map.
Potentially, a watch or break condition could crash if it was unaligned
between mirrors. This might happen if it's not the condition you wanted,
especially. Play it safe.
Probably not worth it for performance reasons, but some semantic cleanup
is good, especially the accidental GetPointer -> writable casts without
using GetPointerWrite.
Using Unchecked on already checked pointers, or when we'd crash anyway
if it returned nullptr, is good for clarity.
* Add range checks in replaced memcpy/memset functions.
Keep seeing especially Replace_memcpy as a semi-rare crash in the
reports. Hopefully this will take care of it, though if games hit this,
they're probably on their way to failing somehow anyway.
* Alternate approach, correctly causing memory exceptions if not ignoring
