threadpool: fix gcc builds : __has_feature needs to be in a separate ifdef

Author: max-krasnyansky

ggml/src/ggml.c

@@ -3204,12 +3204,14 @@ static void ggml_barrier(struct ggml_threadpool * threadpool) {
     // to see an explicit acquire / release sequence to declare all futher accesses
     // as safe.
 
-    #if defined(__has_feature) && __has_feature(thread_sanitizer)
-    #define passed_acquire memory_order_acquire
-    #define passed_release memory_order_release
-    #else
-    #define passed_acquire memory_order_relaxed
-    #define passed_release memory_order_relaxed
+    memory_order passed_acquire = memory_order_relaxed;
+    memory_order passed_release = memory_order_relaxed;
+
+    #if defined(__has_feature)
+    #if __has_feature(thread_sanitizer)
+    passed_acquire = memory_order_acquire;
+    passed_release = memory_order_release;
+    #endif
     #endif
 
     if (atomic_fetch_add_explicit(n_barrier, 1, memory_order_seq_cst) == n_threads - 1) {