Fix thread sanitizer errors surfaced by tests/core/io

core/sync/primitives_atomic.odin

@@ -338,7 +338,7 @@ atomic_sema_wait :: proc "contextless" (s: ^Atomic_Sema) {
 		original_count := atomic_load_explicit(&s.count, .Relaxed)
 		for original_count == 0 {
 			futex_wait(&s.count, u32(original_count))
-			original_count = s.count
+			original_count = atomic_load_explicit(&s.count, .Relaxed)
 		}
 		if original_count == atomic_compare_exchange_strong_explicit(&s.count, original_count, original_count-1, .Acquire, .Acquire) {
 			return

core/thread/thread_pool.odin

@@ -122,9 +122,10 @@ pool_join :: proc(pool: ^Pool) {
 	for started_count < len(pool.threads) {
 		started_count = 0
 		for t in pool.threads {
-			if .Started in t.flags {
+			flags := intrinsics.atomic_load(&t.flags)
+			if .Started in flags {
 				started_count += 1
-				if .Joined not_in t.flags {
+				if .Joined not_in flags {
 					join(t)
 				}
 			}