Exit with error on linux-aarch64 if page size is not 4k

[190n]

What is the problem this feature would solve?

Currently, Bun requires the system page size is 4 kiB in our linux-aarch64 builds. Some aarch64 systems (e.g. Asahi Linux, Raspberry Pi 5, some Ampere servers) are configured with a 16 or 64 kiB page size, and when running Bun on those systems it will crash unpredictably without a helpful error.

What is the feature you are proposing to solve the problem?

Check the page size at startup and exit with an error if it is wrong.

What alternatives have you considered?

Upgrading Zig to a version with ziglang/zig#20511 merged should allow Bun to work on at least 16k page size systems. We may need to configure WebKit differently in order to support 64k pages.