Add test for unknown thread id

tests/regression/51-threadjoins/07-trivial-unknowntid.c

@@ -0,0 +1,34 @@
+//PARAM: --set ana.activated[+] threadJoins
+#include <pthread.h>
+
+int g = 10;
+int h = 10;
+pthread_mutex_t A = PTHREAD_MUTEX_INITIALIZER;
+
+void *t_fun(void *arg) {
+  g++; // RACE!
+  return NULL;
+}
+
+void *t_benign(void *arg) {
+  h++; // NORACE
+  pthread_t id2;
+  pthread_create(&id2, NULL, t_fun, NULL);
+  foo(&id2);
+  pthread_join(id2, NULL);
+  return NULL;
+}
+
+int main(void) {
+  int t;
+
+  pthread_t id2;
+  pthread_create(&id2, NULL, t_benign, NULL);
+  pthread_join(id2, NULL);
+  // t_benign and t_fun should be in here
+
+  g++; // RACE!
+  h++; // NORACE
+
+  return 0;
+}