Add ex-10 from traces

Author: sim642

tests/regression/13-privatized/89-traces-ex-10.c

@@ -0,0 +1,30 @@
+#include <pthread.h>
+#include <goblint.h>
+
+int g = 7; // matches precise read
+pthread_mutex_t A = PTHREAD_MUTEX_INITIALIZER;
+pthread_mutex_t B = PTHREAD_MUTEX_INITIALIZER;
+
+void *t_fun(void *arg) {
+  pthread_mutex_lock(&A);
+  pthread_mutex_lock(&B);
+  g = 42;
+  pthread_mutex_unlock(&B);
+  g = 7;
+  pthread_mutex_unlock(&A);
+  return NULL;
+}
+
+int main(void) {
+  pthread_t id;
+  pthread_create(&id, NULL, t_fun, NULL);
+
+  pthread_mutex_lock(&B);
+  // __goblint_check(g == 7); // UNKNOWN!
+  pthread_mutex_unlock(&B);
+
+  pthread_mutex_lock(&A);
+  pthread_mutex_lock(&B);
+  __goblint_check(g == 7);
+  return 0;
+}