niv musl-wasi: update c5264e2b -> a6489a85

## Changelog for musl-wasi:
Branch: main
Commits: [WebAssembly/wasi-libc@c5264e2b...a6489a85](WebAssembly/wasi-libc@c5264e2...a6489a8)

* [`4bac52ea`](WebAssembly/wasi-libc@4bac52e) Remove trailing backtick in README.md ([WebAssembly/wasi-libc⁠#455](https://togithub.com/WebAssembly/wasi-libc/issues/455))
* [`5a693184`](WebAssembly/wasi-libc@5a69318) add `wasm32-wasi-preview2` target ([WebAssembly/wasi-libc⁠#457](https://togithub.com/WebAssembly/wasi-libc/issues/457))
* [`925ad6d7`](WebAssembly/wasi-libc@925ad6d) CI: include wasi-threads in the sysroot ([WebAssembly/wasi-libc⁠#458](https://togithub.com/WebAssembly/wasi-libc/issues/458))
* [`03b228e4`](WebAssembly/wasi-libc@03b228e) emmalloc: use __heap_end instead of sbrk(0) ([WebAssembly/wasi-libc⁠#462](https://togithub.com/WebAssembly/wasi-libc/issues/462))
* [`47b9db6d`](WebAssembly/wasi-libc@47b9db6) add WASI Preview 2 bindings ([WebAssembly/wasi-libc⁠#460](https://togithub.com/WebAssembly/wasi-libc/issues/460))
* [`cc62fa82`](WebAssembly/wasi-libc@cc62fa8) add stubs for `statvfs`, `chmod`, etc. ([WebAssembly/wasi-libc⁠#463](https://togithub.com/WebAssembly/wasi-libc/issues/463))
* [`a6489a85`](WebAssembly/wasi-libc@a6489a8) test: use the same version of wasmtime and adapter ([WebAssembly/wasi-libc⁠#468](https://togithub.com/WebAssembly/wasi-libc/issues/468))

nix/sources.json

@@ -101,10 +101,10 @@
         "homepage": "https://wasi.dev",
         "owner": "WebAssembly",
         "repo": "wasi-libc",
-        "rev": "c5264e2bbe532994d06b039005f2af91bedcc1a6",
-        "sha256": "1skw2jqzaidr2zbzbjw32b36xvqniwf4if8cr4kbpp8vjvh7j2lr",
+        "rev": "a6489a85633ae36dc1d3ec93f85d27ca242feed0",
+        "sha256": "0sxmf2ws89hgzswypbzqlg3hnjb2qmxlxgnzandk4ljag0n2d59x",
         "type": "tarball",
-        "url": "https://github.com/WebAssembly/wasi-libc/archive/c5264e2bbe532994d06b039005f2af91bedcc1a6.tar.gz",
+        "url": "https://github.com/WebAssembly/wasi-libc/archive/a6489a85633ae36dc1d3ec93f85d27ca242feed0.tar.gz",
         "url_template": "https://github.com/<owner>/<repo>/archive/<rev>.tar.gz"
     },
     "nixpkgs": {