Add support for long jumps using veneer pools

[Sonicadvance1]

For AOT codegen we will want to ensure all of it fits in to a single code region. Add support for veneer pools so we can long jump more than 128MB.

[skmp]

In another direction but a similar issue, due to the way we link blocks right now, the data is intermixed with the code blocks.

For AOT/Code caching, we want to have a couple of pages before or after every X amount of blocks that are dedicated to this, so we can share the code chucks effectively across processes.