lib: c: add pthread implementation

lib/libc/pthread/thread/pthread_exit.c

@@ -0,0 +1,31 @@
+#include "pthread.h"
+
+#include <mango/handle.h>
+#include <mango/task.h>
+#include <pthread.h>
+#include <stdlib.h>
+
+extern void pthread_exit(void *retval)
+{
+	struct __pthread *self = pthread_self();
+	if (!self) {
+		/* TODO: abort(); */
+		return;
+	}
+
+	if (self->thr_flags & THREAD_DETACHED) {
+		kern_handle_t task;
+		kern_handle_t address_space;
+		task_self(&task);
+		task_get_address_space(task, &address_space);
+		kern_handle_close(task);
+
+		__pthread_unmap_exit(
+			address_space,
+			self->thr_map_base,
+			self->thr_map_size);
+	} else {
+		self->thr_result = retval;
+		thread_exit();
+	}
+}