user: implement mlibc as the libc, finally.

It's finally done..

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

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

@@ -0,0 +1,28 @@
+#include <semaphore.h>
+#include <assert.h>
+#include <errno.h>
+
+int main() {
+	sem_t sem;
+	assert(sem_init(&sem, 0, 1) == 0);
+	assert(sem_destroy(&sem) == 0);
+	assert(sem_init(&sem, 0, -1) == -1);
+	assert(errno == EINVAL);
+
+	assert(sem_init(&sem, 0, 3) == 0);
+	assert(sem_trywait(&sem) == 0);
+	assert(sem_trywait(&sem) == 0);
+	assert(sem_trywait(&sem) == 0);
+	assert(sem_trywait(&sem) == -1);
+	assert(errno == EAGAIN);
+	assert(sem_destroy(&sem) == 0);
+
+	sem_init(&sem, 0, 1);
+	assert(sem_wait(&sem) == 0);
+	assert(sem_trywait(&sem) == -1);
+	assert(sem_post(&sem) == 0);
+	assert(sem_wait(&sem) == 0);
+	assert(sem_destroy(&sem) == 0);
+
+	return 0;
+}