Apple Silicon build emits error: AL lib: (EE) FillCPUCaps: Failed to open /proc/cpuinfo, cannot check for NEON support

**Issue description:**

After building and launching the editor on Apple Silicon, the terminal will print:
```AL lib: (EE) FillCPUCaps: Failed to open /proc/cpuinfo, cannot check for NEON support```

The editor does not crash, and things seem to function correctly anyways, but I am not sure what the ramifications of this are.

From what I understand /proc/cpuinfo is a linux location, and I believe neon support can be queried on Apple Silicon via:
```
>>> sysctl -a | grep neon
hw.optional.neon: 1
hw.optional.neon_hpfp: 1
hw.optional.neon_fp16: 1
```

There seems to be more info here: https://developer.apple.com/documentation/kernel/1387446-sysctlbyname/determining_instruction_set_characteristics

**Steps to reproduce:**

Device: M2 Pro

Build from source and launch the editor

**Minimal reproduction project:**

N/A

**Flax version:**

Commit SHA: 778dd2d3f00a89898dc3ce3506665412702f61ae