## What does this PR do?
Switch `Bun.hash.crc32` to use `zlib`'s CRC32 implementation. Bun
already links `zlib`, which provides highly optimized,
hardware-accelerated CRC32. Because `zlib.crc32` takes a 32-bit length,
chunk large inputs to avoid truncation/regressions on buffers >4GB.
Note: This was tried before (PR #12164 by Jarred), which switched CRC32
to zlib for speed. This proposal keeps that approach and adds explicit
chunking to avoid the >4GB length pitfall.
**Problem:** `Bun.hash.crc32` is a significant outlier in
microbenchmarks compared to other hash functions (about 21x slower than
`zlib.crc32` in a 1MB test on M1).
**Root cause:** `Bun.hash.crc32` uses Zig's `std.hash.Crc32`
implementation, which is software-only and does not leverage hardware
acceleration (e.g., `PCLMULQDQ` on x86 or `CRC32` instructions on ARM).
**Implementation:**
https://github.com/oven-sh/bun/blob/main/src/bun.js/api/HashObject.zig
```zig
pub const crc32 = hashWrap(struct {
pub fn hash(seed: u32, bytes: []const u8) u32 {
// zlib takes a 32-bit length, so chunk large inputs to avoid truncation.
var crc: u64 = seed;
var offset: usize = 0;
while (offset < bytes.len) {
const remaining = bytes.len - offset;
const max_len: usize = std.math.maxInt(u32);
const chunk_len: u32 = if (remaining > max_len) @intCast(max_len) else @intCast(remaining);
crc = bun.zlib.crc32(crc, bytes.ptr + offset, chunk_len);
offset += chunk_len;
}
return @intCast(crc);
}
});
```
### How did you verify your code works?
**Benchmark (1MB payload):**
- **Before:** Bun 1.3.5 `Bun.hash.crc32` = 2,644,444 ns/op vs
`zlib.crc32` = 124,324 ns/op (~21x slower)
- **After (local bun-debug):** `Bun.hash.crc32` = 360,591 ns/op vs
`zlib.crc32` = 359,069 ns/op (~1.0x), results match
## Test environment
- **Machine:** MacBook Pro 13" (M1, 2020)
- **OS:** macOS 15.7.3
- **Baseline Bun:** 1.3.5
- **After Bun:** local `bun-debug` (build/debug)
d3a5f2eef2
