ggml : use atomic_flag for critical section

ggml.c

@@ -2883,24 +2883,20 @@ struct ggml_state {
 
 // global state
 static struct ggml_state g_state;
-static atomic_int g_state_barrier = 0;
+static atomic_flag g_state_critical = ATOMIC_FLAG_INIT;
 
 // barrier via spin lock
 inline static void ggml_critical_section_start(void) {
-    int processing = atomic_fetch_add(&g_state_barrier, 1);
-
-    while (processing > 0) {
-        // wait for other threads to finish
-        atomic_fetch_sub(&g_state_barrier, 1);
-        sched_yield(); // TODO: reconsider this
-        processing = atomic_fetch_add(&g_state_barrier, 1);
+    while (atomic_flag_test_and_set(&g_state_critical)) {
+        // spin
+        sched_yield();
     }
 }
 
 // TODO: make this somehow automatically executed
 //       some sort of "sentry" mechanism
 inline static void ggml_critical_section_end(void) {
-    atomic_fetch_sub(&g_state_barrier, 1);
+    atomic_flag_clear(&g_state_critical);
 }
 
 #if defined(__gnu_linux__)