Minor changes to threading

- Renamed `cpp11_thread.cpp` to `thread.cpp`
- Removed features that are only supported by Win32 threads (`thread_wait` with timeout and mutex with spinlock)
- Fixed formatting in `thread.cpp`

src/unix/unix_thread.c

@@ -53,9 +53,9 @@ thread_create(void (*thread_rout)(void *param), void *param)
 
 
 int
-thread_wait(thread_t *arg, int timeout)
+thread_wait(thread_t *arg)
 {
-    return pthread_join(*(pthread_t*)(arg), NULL) != 0;
+    return pthread_join(*(pthread_t*)(arg), NULL);
 }
 
 
@@ -144,14 +144,6 @@ thread_create_mutex(void)
 }
 
 
-mutex_t *
-thread_create_mutex_with_spin_count(unsigned int spin_count)
-{
-    /* Setting spin count of a mutex is not possible with pthreads. */
-    return thread_create_mutex();
-}
-
-
 int
 thread_wait_mutex(mutex_t *_mutex)
 {