Merge pull request #180 from avsm/fix-mpopcnt

fix -mpopcnt compilation failure on macOS/aarch64 10.4

Author: dkalinichenko-js

src/discover/discover.ml

@@ -14,7 +14,11 @@ let () =
   main
     ~name:"discover"
     ~args:[ "-o", Set_string output, "FILENAME output file" ]
-    (fun c ->
-      let has_popcnt = c_test c ~c_flags:[ "-mpopcnt" ] program in
+    (fun _c ->
+      let f,oc = Filename.open_temp_file "baseconf" ".c" in
+      let has_popcnt =
+        Fun.protect ~finally:(fun () -> close_out oc; Sys.remove f)
+          (fun () -> Out_channel.(output_string oc program; flush oc);
+            Sys.command (Printf.sprintf "cc %s -mpopcnt -o /dev/null >/dev/null 2>&1" f) = 0) in
       Flags.write_sexp !output (if has_popcnt then [ "-mpopcnt" ] else []))
 ;;