user: implement mlibc as the libc, finally.

It's finally done..

Signed-off-by: kaguya <vpshinomiya@protonmail.com>

user/include/mlibc/tests/posix/pthread_barrier.c

@@ -0,0 +1,58 @@
+#include <pthread.h>
+#include <unistd.h>
+#include <assert.h>
+
+pthread_barrier_t barrier;
+_Atomic int hitBarrierCount, pastBarrierCount;
+
+static void *worker(void *arg) {
+	(void)arg;
+	hitBarrierCount++;
+	pthread_barrier_wait(&barrier);
+	pastBarrierCount++;
+	return NULL;
+}
+
+int main() {
+	// pthread_barrierattr_t
+	pthread_barrierattr_t attr;
+	pthread_barrierattr_init(&attr);
+
+	int pshared;
+	pthread_barrierattr_getpshared(&attr, &pshared);
+	assert(pshared == PTHREAD_PROCESS_PRIVATE);
+
+	pthread_barrierattr_setpshared(&attr, PTHREAD_PROCESS_SHARED);
+	pthread_barrierattr_getpshared(&attr, &pshared);
+	assert(pshared == PTHREAD_PROCESS_SHARED);
+
+	pthread_barrierattr_setpshared(&attr, PTHREAD_PROCESS_PRIVATE);
+	pthread_barrierattr_getpshared(&attr, &pshared);
+	assert(pshared == PTHREAD_PROCESS_PRIVATE);
+
+	// pthread_barrier_t
+	pthread_barrier_init(&barrier, &attr, 3);
+	pthread_barrierattr_destroy(&attr);
+
+	pthread_t thread1;
+	int ret = pthread_create(&thread1, NULL, &worker, NULL);
+	assert(!ret);
+
+	pthread_t thread2;
+	ret = pthread_create(&thread2, NULL, &worker, NULL);
+	assert(!ret);
+
+	sleep(1);
+
+	// Make sure the barrier actually stops threads from proceeding.
+	assert(pastBarrierCount == 0);
+	assert(hitBarrierCount <= 2);
+
+	hitBarrierCount++;
+	pthread_barrier_wait(&barrier);
+	assert(hitBarrierCount == 3);
+
+	pthread_barrier_destroy(&barrier);
+
+	return 0;
+}