LibC: Make pthread_barrier safe

It used to deadlock and it was not safe if more threads than the target
were attempting to wait on it.

userspace/libraries/LibC/include/bits/types/pthread_types.h

@@ -28,17 +28,6 @@ typedef struct
 	unsigned lock_depth;
 } pthread_mutex_t;
 
-typedef struct
-{
-	int shared;
-} pthread_barrierattr_t;
-typedef struct
-{
-	pthread_barrierattr_t attr;
-	unsigned target;
-	unsigned waiting;
-} pthread_barrier_t;
-
 typedef struct
 {
 	int clock;
@@ -56,6 +45,20 @@ typedef struct
 	struct _pthread_cond_block* block_list;
 } pthread_cond_t;
 
+typedef struct
+{
+	int shared;
+} pthread_barrierattr_t;
+typedef struct
+{
+	pthread_barrierattr_t attr;
+	pthread_mutex_t lock;
+	pthread_cond_t cond;
+	unsigned target;
+	unsigned waiting;
+	unsigned generation;
+} pthread_barrier_t;
+
 typedef struct
 {
 	int shared;