Crystal 1.22 adds native event loops and faster DWARF parsing

Crystal 1.22.0 makes a native system-selector event loop the default across all targets, leaving libevent as an opt-in fallback.

The release also refactors DWARF parsing to scan sections on demand, build an index once, and cache decoded backtrace lines.

Other changes include LLVM 23 and 24 support, Tier 1 status for aarch64 Linux targets, and immediate exit on EPIPE writes to standard output or error.