Fix arch detection

Author: chadrik

src/python/stubs/generate_stubs_local.py

@@ -24,8 +24,14 @@ def main():
     if platform.system() == "Darwin":
         # On Mac, `uname -m`,  $CMAKE_HOST_SYSTEM_PROCESSOR, and platform.machine() returns
         # x86_64 even on arm64 processors (i.e. Apple Silicon) if cmake or python is running under
-        # emulation (Rosetta).
-        arch = subprocess.check_output(["sysctl", "-n", "hw.machine"], text=True).strip()
+        # emulation (Rosetta). sysctl.proc_translated tells us if we're under emulation.
+        arch = subprocess.check_output(["uname", "-m"], text=True).strip()
+        if arch == "x86_64":
+            process_uses_emulation = subprocess.check_output(
+                ["sysctl", "-in", "sysctl.proc_translated"], text=True
+            ).strip()
+            if process_uses_emulation == "1":
+                arch = "arm64"
     else:
         arch = platform.machine()
     if arch == "arm64":