lib: fs: implement memory-mapped file i/o

lib/libfs/interface/close.c

@@ -0,0 +1,14 @@
+#include "../interface.h"
+
+#include <errno.h>
+#include <mango/status.h>
+
+extern kern_status_t fs_msg_close(
+	xpc_context_t *ctx,
+	const xpc_endpoint_t *sender,
+	int *out_err,
+	void *arg)
+{
+	*out_err = ENOSYS;
+	return KERN_OK;
+}