regressions/spinlock: Do not rely on RMW for counter update.

This makes it more likely to trigger load-store/store-load re-ordering
across critical sections.

regressions/ck_spinlock/validate/validate.h

@@ -87,16 +87,16 @@ thread(void *null CK_CC_UNUSED)
 			ck_error("is_locked operation failed.");
 #endif
 
-		ck_pr_inc_uint(&locked);
-		ck_pr_inc_uint(&locked);
-		ck_pr_inc_uint(&locked);
-		ck_pr_inc_uint(&locked);
-		ck_pr_inc_uint(&locked);
-		ck_pr_inc_uint(&locked);
-		ck_pr_inc_uint(&locked);
-		ck_pr_inc_uint(&locked);
-		ck_pr_inc_uint(&locked);
-		ck_pr_inc_uint(&locked);
+		ck_pr_store_uint(&locked, locked + 1);
+		ck_pr_store_uint(&locked, locked + 1);
+		ck_pr_store_uint(&locked, locked + 1);
+		ck_pr_store_uint(&locked, locked + 1);
+		ck_pr_store_uint(&locked, locked + 1);
+		ck_pr_store_uint(&locked, locked + 1);
+		ck_pr_store_uint(&locked, locked + 1);
+		ck_pr_store_uint(&locked, locked + 1);
+		ck_pr_store_uint(&locked, locked + 1);
+		ck_pr_store_uint(&locked, locked + 1);
 
 		j = ck_pr_load_uint(&locked);
 
@@ -105,19 +105,18 @@ thread(void *null CK_CC_UNUSED)
 			exit(EXIT_FAILURE);
 		}
 
-		ck_pr_dec_uint(&locked);
-		ck_pr_dec_uint(&locked);
-		ck_pr_dec_uint(&locked);
-		ck_pr_dec_uint(&locked);
-		ck_pr_dec_uint(&locked);
-		ck_pr_dec_uint(&locked);
-		ck_pr_dec_uint(&locked);
-		ck_pr_dec_uint(&locked);
-		ck_pr_dec_uint(&locked);
-		ck_pr_dec_uint(&locked);
+		ck_pr_store_uint(&locked, locked - 1);
+		ck_pr_store_uint(&locked, locked - 1);
+		ck_pr_store_uint(&locked, locked - 1);
+		ck_pr_store_uint(&locked, locked - 1);
+		ck_pr_store_uint(&locked, locked - 1);
+		ck_pr_store_uint(&locked, locked - 1);
+		ck_pr_store_uint(&locked, locked - 1);
+		ck_pr_store_uint(&locked, locked - 1);
+		ck_pr_store_uint(&locked, locked - 1);
+		ck_pr_store_uint(&locked, locked - 1);
 
 		UNLOCK;
-
 		LOCK;
 
 		j = ck_pr_load_uint(&locked);